Force generation mechanism

ABSTRACT

A damper apparatus ( 12 ) as the force generation mechanism mounted between a vehicle body ( 2 ) and a bogie ( 5 ) includes an attenuation damper ( 13 ), an electric damper ( 14 ), and a gear apparatus ( 15 ). The attenuation damper includes a rod protruding from a cylinder, and generates a damping force by converting motion energy of a forward or backward movement of the rod into heat energy. The electric damper includes a stator, and a movable element linearly movable relative to the stator. The gear apparatus is disposed between the attenuation damper and the electric damper, and can mechanically switch the attenuation damper and the electric damper between a series connection and a parallel connection. The gear apparatus switches a connection state between the attenuation damper and the electric damper according to the condition.

TECHNICAL FIELD

The present invention relates to a force generation mechanism preferablyused, as, for example, a damper apparatus for a vehicle such as arailway vehicle and an automobile.

BACKGROUND ART

Generally, a damper apparatus such as a damping force adjustable shockabsorber is mounted on a vehicle such as a railway vehicle and anautomobile between a sprung side (a vehicle body side) and an unsprungside (a bogie side or an axle side). As one type of such a damperapparatus, there is known a damper apparatus configured to include ahydraulic damper and an electromagnetic damper arranged in parallel (forexample, refer to Patent Document 1).

CITATION LIST Patent Literature

Patent Document 1: Japanese Patent Application Public Disclosure No.2003-252203 (Japanese Patent No. 4085368)

SUMMARY OF INVENTION

According to the conventional technique discussed in Patent Document 1,the hydraulic damper and the electromagnetic damper are arranged inparallel. On the other hand, it is desirable to be able to use only anyone of the hydraulic damper (an attenuation damper) and theelectromagnetic damper (an electric damper), and use both of them (theattenuation damper and the electric damper) in parallel according to anoperation condition or the like.

The present invention has been contrived in consideration of thedrawback with the above-described conventional technique, and an objectof the present invention is to provide a force generation mechanismcapable of generating a desired force according to a condition.

To achieve the above-described object, the present invention is a forcegeneration mechanism configured to be mounted between two members thatare one member and the other member relatively movable to each other.The force generation mechanism includes a plurality of direct-driveforce generation units, and a switching unit disposed between one andanother of the force generation units and capable of mechanicallyswitching the one and the another force generation units between aseries connection and a parallel connection.

According to the present invention, it is possible to generate a desiredforce according to a condition.

BRIEF DESCRIPTIONS OF DRAWINGS

FIG. 1 is a cross-sectional view illustrating a railway vehicle with aforce generation mechanism according to a first embodiment of thepresent invention mounted thereon.

FIG. 2 is a cross-sectional view illustrating a bogie, the forcegeneration mechanism, and the like taken along a direction indicated byarrows II-II illustrated in FIG. 1.

FIG. 3 is a perspective view schematically illustrating a switching unitand the like of the force generation mechanism.

FIG. 4 is a perspective view schematically illustrating the bogie, theforce generation mechanism, and the like.

FIGS. 5(A) to (D) are plan views each schematically illustrating theforce generation mechanism for each switched state (each operation mode)as viewed from the same direction as FIG. 2.

FIGS. 6(A) to (D) each schematically illustrate the force generationmechanism for each switched state for facilitating better understandingof an operation principle of the force generation mechanism.

FIG. 7 schematically illustrates the force generation mechanism togetherwith variables indicating its state for facilitating betterunderstanding of an operation of the force generation mechanism.

FIG. 8 is a block diagram illustrating a controller illustrated in FIG.1.

FIG. 9 is a flowchart illustrating a content of control by thecontroller illustrated in FIG. 1.

FIG. 10 is a flowchart illustrating a content of processing in a normaloperation mode illustrated in FIG. 9.

FIG. 11 is a flowchart illustrating a content of processing in a safemode 1 illustrated in FIG. 9.

FIG. 12 is a flowchart illustrating a content of processing in a safemode 2 illustrated in FIG. 9.

FIG. 13 is a flowchart illustrating a content of malfunctiondetermination processing illustrated in FIG. 10.

FIG. 14 is a flowchart illustrating a content of processing fordetermining whether an electric damper is stuck that is illustrated inFIG. 11.

FIG. 15 is a transverse cross-sectional view illustrating a forcegeneration mechanism according to a second embodiment of the presentinvention.

FIGS. 16(A) to (D) each schematically illustrate the force generationmechanism for each switched state for facilitating better understandingof an operation principle of the force generation mechanism.

FIG. 17 is a transverse cross-sectional view illustrating a forcegeneration mechanism according to a third embodiment of the presentinvention.

FIG. 18 schematically illustrates a force generation mechanism accordingto a first modification of the present invention as viewed from the samedirection as FIGS. 6(A) to 6(D).

FIG. 19 schematically illustrates a force generation mechanism accordingto a second modification of the present invention as viewed from thesame direction as FIGS. 16(A) to (D).

FIG. 20 schematically illustrates a force generation mechanism accordingto a third modification of the present invention as viewed from the samedirection as FIGS. 6(A) to (D).

FIG. 21 schematically illustrates a force generation mechanism accordingto a fourth modification of the present invention as viewed from thesame direction as FIGS. 16(A) to (D).

FIG. 22 schematically illustrates a force generation mechanism accordingto a fifth modification of the present invention as viewed from the samedirection as FIGS. 6(A) to (D).

FIG. 23 schematically illustrates a force generation mechanism accordingto a sixth modification of the present invention as viewed from the samedirection as FIGS. 16(A) to (D).

FIG. 24 schematically illustrates a force generation mechanism accordingto a seventh modification of the present invention as viewed from thesame direction as FIGS. 16(A) to (D).

FIG. 25 schematically illustrates a force generation mechanism accordingto an eighth modification of the present invention as viewed from thesame direction as FIGS. 16(A) to (D).

DESCRIPTION OF EMBODIMENTS

In the following description, force generation mechanisms according toembodiments of the present invention will be described in detail withreference to the accompanying drawings based on an example in which theforce generation mechanism is applied to a damper apparatus mounted on,for example, a railway vehicle.

FIGS. 1 to 14 illustrate a first embodiment of the present invention.Referring to the drawings, a railway vehicle 1 generally includes avehicle body 2 where, for example, passengers and crews axe aboard, anda bogie 5 disposed below the vehicle body 2 and guided by two rails 4via vehicle wheels 3. FIGS. 1 and 4 illustrate only a single bogie 5mounted on one side of the vehicle body 2 in a front-back direction, butactually, bogies 5 are mounted on both sides of the vehicle body 2 inthe front-back direction, respectively.

A central pin 6 is fixedly provided on a bottom of the vehicle body 2,more specifically, at a portion on a bottom surface side of the vehiclebody 2 that faces each of the bogies 5 in a vertical direction, so as toprotrude downwardly from the bottom surface of the vehicle body 2. Apinion 19 of a gear apparatus 15 included in a damper apparatus 12 thatwill be described below is mounted on this central pin 6 via a bearing 7such as a rolling bearing.

On the other hand, the bogie 5 generally includes a left side bolster 5Aand a right side bolster 5B disposed so as to be spaced apart from eachother in a left-right direction, and a front transverse bolster 5C, acentral front transverse bolster 5D, a central back transverse bolster5E, and a back transverse bolster 5F connecting these left and rightside bolsters 5A and 5B. Then, the left and right side bolsters 5A and5B rotatably support axles 8 with the vehicle wheels 3 mounted thereonvia bearing apparatuses 9.

Further, a traction apparatus (not illustrated), which transmits atraction force and a control force applied in the front-back directionbetween the vehicle body 2 and the bogie 5, is disposed between thecentral pin 6 mounted on the vehicle body 2 and the central transversebolsters 5D and 5E of the bogie 5. The traction apparatus includes alink mechanism having, for example, an I shape or a Z shape as viewedfrom above. Then, the traction apparatus connects the central pint 6 ofthe vehicle body 2 and the central transverse bolsters 5D and 5E of thebogie 5 so as to be able to transmit the traction force and the controlforce between the vehicle body 2 and the bogie 5 while allowing thevehicle body 2 to be displaced (moved) relative to the bogie 5 in thevertical direction, the left-right direction, a yaw (a bogie turning)direction, and a pitching direction.

Further, a mounting bracket 5G is disposed at the central fronttransverse bolster 5D of the bogie 5 at a position closer to one side inthe left-right direction (the right side in the example illustrated inthe drawings). An electric damper 14 (a stator 14A thereof) included inthe damper apparatus 12 that will be described below is swingablymounted on this mounting bracket 5G via a pin-equipped rubber bush 14D.On the other hand, a mounting bracket 5H is disposed on the central backtransverse bolster 5E at a position closer to the other side in theleft-right direction (the left side in the example illustrated in thedrawings). An attenuation damper 13 (a cylinder 13A thereof) included inthe damper apparatus 12 that will be described below is swingablymounted on this mounting bracket 5H via a pin-equipped rubber bush 13D.

A suspension apparatus 10 is disposed between the vehicle body 2, whichcorresponds to a sprung side, and the bogie 5, which corresponds to anunsprung side. The suspension apparatus 10 generally includes pneumaticsprings 11 supporting the vehicle body 2 swingably relative to the bogie5 in the vertical direction and the left-right direction, and the damperapparatus 12 disposed between the vehicle body 2 (the central pin 6mounted thereon) and the bogie 5 (the central transverse bolsters 5D and5E thereof) and serving as a force generation mechanism. A pair ofpneumatic springs 11 are disposed between the vehicle body 2 and thebogie 5 so as to be spaced apart from each other in the left-rightdirection. Since the bogies 5 are disposed on the both sides of thevehicle body 2 in the front-back direction, respectively, this railwayvehicle 1 is configured to include two suspension apparatuses 10 intotal, i.e., four pneumatic springs 11 and two damper apparatuses 12 intotal for each vehicle (for each vehicle body).

Next, the damper apparatus 12, which damps a vibration between thevehicle body 2 and the bogie 5, will be described.

The damper apparatus 12 as the force generation mechanism is mountedbetween two members, the vehicle body 2 as one of relatively movingmembers, and the bogie 5 as the other of the relatively moving members.The damper apparatus 12 (actively and passively) generates a force (athrust force and a damping force) between the vehicle body 2 and thebogie 5 to damp a vibration (a relative displacement) between thevehicle body 2 and the bogie 5. More specifically, the damper apparatus12 is configured as a left-right movement damper apparatus to generate aforce (a thrust force and a damping force) for reducing a vibration ofthe vehicle body 2 relative to the bogie 5 in the left-right directionto thereby damp the vibration of the vehicle body 2 in the left-rightdirection.

The damper apparatus 12 includes a plurality of direct-drive forcegeneration units, more specifically, the attenuation damper 13 as oneforce generation unit and the electric damper 14 as another forcegeneration unit, and a gear apparatus 15 as a switching unit is disposedbetween these attenuation damper 13 and electric damper 14. In otherwords, the damper apparatus 12 generally includes the attenuation damper13 as the force generation unit, the electric damper 14 as the forcegeneration unit, and the gear apparatus 15 as the switching unit.

The attenuation damper 13 as the one force generation unit includes arod 13B protruding from, the cylinder 13A, and generates a damping forceby converting motion energy of a forward or backward movement of the rod13B into heat energy. More specifically, the attenuation damper 13 isrealized by, for example, a fluid pressure damper (a fluid pressureshock absorber) such as a hydraulic damper (a hydraulic shock absorber)that generates a damping force with use of hydraulic fluid (a viscousresistance thereof) such as hydraulic oil, or a fractional damper (africtional shock absorber) that generates a damping force with use of africtional resistance generated during a sliding movement betweenslidable surfaces. In FIGS. 3 to 6 (and FIGS. 16 and 18 to 25 that willbe described below), a text “H-DMP”, which indicates the hydraulicdamper as a representative example of the attenuation damper 13, isadded to the attenuation damper 13 to allow the attenuation damper 13 tobe easily distinguished from the electric damper 14 that will bedescribed below.

The attenuation damper 13 generally includes the cylindrical cylinder13A sealingly containing hydraulic fluid, a piston (not illustrated)displaceably contained in the cylinder 13A, the rod 13B having one-endside (a right-end side in FIGS. 1 to 5) protruding from one end of thecylinder 13A, and an opposite-end side (a left-end side in FIGS. 1 to 5)fixedly attached to the piston, and a damping force generation mechanism(not illustrated) disposed in the cylinder 13A including the piston andconfigured to damp a flow of the hydraulic fluid to thereby generate adamping force.

A mounting eye 13C for mounting a proximal end of the cylinder 13A ontothe bogie 5 is provided at the proximal end (the left end in FIGS. 1 to5) of the cylinder 13A, which corresponds to a bottom side of theattenuation damper 13. In this case, the pin-equipped rubber bush 13D isfixedly attached inside the mounting eye 13C, and a mounting pin of thispin-equipped rubber bush 13D is fixed to the mounting bracket 5H of thebogie 5 with use of a bolt or the like.

On the other hand, a mounting eye 13E for mounting a distal end of therod 13B onto a rack 18 that will be described below is provided at thedistal end (the right end in FIG. 1 to 5) of the rod 13B, whichcorresponds to a rod side of the attenuation damper 13. In this case, apin-equipped rubber bush 13F is fixedly attached inside the mounting eye13E, and a mounting pin of this pin-equipped rubber bush 13F is fixed toa damper mounting portion 18C of the rack 18 with use of a bolt or thelike. The pin-equipped rubber bushes 13D and 13F absorb forces generatedfrom rolling of the vehicle body 2 and yawing of the bogie 5 by elasticdeformation of the rubber bushes.

Further, an attenuation damper lock apparatus 13G (refer to FIGS. 6 and8) is disposed at the attenuation damper 13 (or between the rod 13B ofthe attenuation damper 13 and the bogie 5) for prohibiting (blocking) arelative movement between the cylinder 13A and the rod 13B (a forward orbackward movement of the rod 13B relative to the cylinder 13A). Thisattenuation damper lock apparatus 13G variably adjusts a resistanceforce against a relative displacement between the cylinder 13A and therod 13B, and the relative movement between the cylinder 13A and the rod13B is prohibited (locked) when the resistance force is maximized.

This attenuation damper lock apparatus 13G can employ, for example, aconfiguration that prohibits (forbids) a flow of the hydraulic fluid inthe cylinder 13A, a configuration that mechanically fixes the rod 13Brelative to the cylinder 13A, or a configuration that mechanically fixesthe rod 13B relative to the bogie 5, as a configuration for maximizingthe resistance force (locking the attenuation damper 13). In otherwords, the attenuation damper lock apparatus 13G can employ any ofvarious kinds of configurations (a lock configuration and a brakeconfiguration), such, as a configuration using friction, a configurationusing a pin (engagement), and a configuration using a hydraulicpressure, as long as this configuration can acquire a requiredresistance force.

As illustrated in FIG. 8, the attenuation damper lock apparatus 13G isconnected to a controller 23 that will be described below, and isswitched between a locking state and an unlocking state (a releasingstate) according to an instruction signal (a control signal) from thiscontroller 23. For example, the attenuation damper lock apparatus 13G isswitched to the locking state according to a signal from the controller23 when the railway vehicle 1 is in a normal operation mode illustratedin FIGS. 5(B) and 6(B) that will be described below. In this case, it ispossible to realize an operation state (an operation mode) using theelectric damper 14 alone as will be described below.

The electric damper 14 as the another force generation unit includes thestator 14A, and a movable element 14B movable relative to this stator 14in a linear direction. More specifically, the electric damper 14 isrealized by an electric actuator that generates a force based on asupply of power (power energization), such as a linear motor (a linearactuator) such as a three-phase linear synchronous motor that generatesa linear thrust force based on a force generated from attraction andrepulsion between an armature (a coil thereof) and a permanent magnet.In FIGS. 3 to 6 (and FIGS. 16 and 18 to 25 that will be describedbelow), a text “ACTR”, which indicates the electric actuator as arepresentative example of the electric damper 14, is added to theelectric damper 14 to allow the electric damper 14 to be easilydistinguished from the attenuation damper 13.

The electric damper 14 generally includes the cylindrical stator 14Aincluding an armature with a plurality of coils provided thereon, andthe movable element 14B including a plurality of cylindrical permanentmagnets arranged side by side in an axial direction. Upon a supply of acurrent to the coils of the armature, an electromagnetic force isgenerated between the current flowing through the respective coils andthe permanent magnets, and a thrust force (a damping force) is generatedfrom this electromagnetic force. This thrust force is adjusted accordingto a thrust force instruction value (a control signal or an instructioncurrent) output from the controller 23 (refer to FIG. 8) that will bedescribed below.

A mounting eye 14C for mounting a proximal end of the stator 14A ontothe mounting bracket 5G of the bogie 5 is provided at the proximal end(the right end in FIGS. 1 to 5) of the stator 14A. In this case, thepin-equipped rubber bush 14D is fixedly attached inside the mounting eye14C, and a mounting pin of this pin-equipped rubber bush 14D is fixed tothe mounting bracket 5G of the bogie 5 with use of a bolt or the like.

On the other hand, a mounting eye 14E for mounting a distal end of themovable element 14B onto a rack 17 that will be described below isprovided at the distal end (the left end as shown in FIG. 1 to 5) of themovable element 14B of the electric damper 14. In this case, apin-equipped rubber bush 14F is fixedly attached inside the mounting eye14E, and a mounting pin of this pin-equipped rubber bush 14F is fixed toa damper mounting portion 17C of the rack 17 with use of a bolt or thelike. The pin-equipped rubber bushes 14D and 14F absorb a forcegenerated from rolling of the vehicle body 2 and yawing of the bogie 5by elastic deformation of the rubber bushes.

An electric damper lock apparatus, which prohibits (forbids) a relativemovement between the stator 14A and the movable element 14B (a forwardor backward movement of the movable element 14B relative to the stator14A), can be disposed at the electric damper 14 (or between the movableelement 14B of the electric damper 14 and the bogie 5), if necessary. Inthis case, the electric damper lock apparatus can be configured to beable to realize a locking state according to an instruction (a signal)from the controller 23. Due to this configuration, the electric damperlock apparatus can create a state of a safe mode 2 illustrated in FIGS.5(C) and 6(C) that will be described below, i.e., a state equivalent tosuch a state that the stator 14A and the movable element 14B of theelectric damper 14 are fixed to each other (stuck to each other),according to the instruction from the controller 23. In other words,providing the electric damper lock apparatus allows the electric damper14 to be locked (allows the movable element 14B to be fixed) accordingto the instruction from the controller 23, thereby creating an operationstate (an operation mode) using the attenuation damper 13 alone.

The gear apparatus 15 as the switching unit is disposed between theattenuation damper 13 and the electric damper 14. The gear apparatus 15allows the attenuation damper 13 and the electric damper 14 to bemechanically switched between a series connection and a parallelconnection. Therefore, the gear apparatus 15 generally includes a gearcase 16, the two racks 17 and 18, the pinion 19, and a pinion brakeapparatus 20.

The gear case 16 is formed as a generally cuboid hollow box, and ismounted below the vehicle body 2 with the central pin 6 inserted(penetrating) at a center of the gear case 16. The gear case 16 includesa top plate portion 16A (refer to FIG. 1) facing the bottom surface ofthe vehicle body 2, a bottom plate portion 16B opposite of the racks 17and 18 and the pinion 19 from the top plate portion 16A in the verticaldirection, and a front plate portion 16C, a back plate portion 16D, aleft plate portion 16E, and a right plate portion 16F surrounding theracks 17 and 18 and the pinion 19 on four sides between the top plateportion 16A and the bottom plate portion 16B.

Openings (not illustrated) are formed at central positions of the topplate portion 16A and the bottom plate portion 16B for insertion of thecentral pin 6, respectively. The top plate portion 16A and the bottomplate portion 16B are fixed to the central pin 16, which is the vehiclebody side, with the central pin 16 inserted through their respectiveopenings. An opening 16C1 is formed at the front plate portion 16C forinsertion of an arm portion 17B of the rack 17, and an opening 16D1 isformed at the back plate portion 16D for insertion of an arm portion 18Bof the rack 18. Relief holes 16E1 and 16F1 are formed at the left plateportion 16E and the right plate portion 16F for displaceable insertionof the racks 17 and 18, respectively.

The two racks (rack gears) 17 and 18 are disposed inside the gear case16 so as to sandwich the pinion 19 in the front-back direction of thevehicle body 2. These two racks 17 and 18 are supported so as to bedisplaceable in the gear case 16 in the left-right direction vianot-illustrated bearings, slidable members, and the like. The threemembers, the pair of racks 17 and 18 and the pinion 19 included in thegear apparatus 15, are mounted (attached) on the three elements, theelectric damper 14, the attenuation damper 13, and the vehicle body 2,respectively, and the present embodiment is configured in such a mannerthat the racks 17 and 18 are mounted on the movable element 14B of theelectric damper 14 and the rod 13B of the attenuation damper 13,respectively, and the pinion 19 is mounted on the vehicle body 2.

The rack 17 on the front side generally includes a tooth portion (a rackportion) 17A extending in the left-right direction and meshed with thepinion 19, and the arm portion 17B forwardly extending from a centralposition of the tooth portion 17A in the left-right direction. Adistal-end side of the arm portion 17B protrudes from the opening 16C1of the gear case 16, and the damper mounting portion 17C is provided ata distal end thereof. The mounting eye 14E of the movable element 14B ofthe electric damper 14 is mounted on this damper mounting portion 17Cvia the pin-equipped rubber bush 14F.

The rack 18 on the back side generally includes a tooth portion (a rackportion) 18A extending in the left-right direction and meshed with thepinion 19, and the arm portion 18B backwardly extending from a centralposition of the tooth portion 18A in the left-right direction. Adistal-end side of the arm portion 18C protrudes from the opening 16D1of the gear case 16, and the damper mounting portion 18C is provided ata distal end thereof. The mounting eye 13E of the rod 13B of theattenuation damper 13 is mounted on this damper mounting portion 18C viathe pin-equipped rubber bush 13F.

The pinion (pinion gear) 19 is formed as an annular member including atooth portion 19A meshed with the racks 17 and 18 on an outercircumferential side thereof, and is concentrically disposed with arotational center (a center when turning) of the bogie 5. In this case,the pinion 19 is disposed so as to surround the central pin 6 downwardlyextending from the vehicle body 2. More specifically, the pinion 19 ismounted on the central pin 6 so as to be rotatable relative to thiscentral pin 6 via the rolling bearing 7. Then, the pinion 19 (the toothportion 19A thereof) is meshed with the respective racks 17 and 18 (thetooth portions 17A and 18B) at two positions spaced apart from eachother by 180 degrees in the front-back direction.

Therefore, when the pinion brake apparatus 20 that will be describedbelow releases the pinion 19 (when the pinion 19 is freely rotatable), adisplacement of the rack 17 or the rack 18 in the left-right directioncauses the pinion 19 to rotate around the central pin 6 according tothis displacement. In this case, for example, when the attenuationdamper lock apparatus 13G is in the locking state, i.e., the rod 13B isfixed relative to the cylinder 13A, the rack 18 is fixed relative to thebogie 5. Therefore, when the rack 17 is displaced in the left-rightdirection based on a thrust force of the electric damper 14, the pinion19 is displaced in the left-right direction while rotating around thecentral pin 6. Detailed operations of the attenuation damper 13, theelectric damper 14, the racks 17 and 18, and the pinion 19 will bedescribed below.

The pinion brake apparatus 20 (refer to FIGS. 2 and 8), whichconstitutes the gear apparatus 15 together with the racks 17 and 18 andthe pinion 19, is disposed inside the gear case 16, for example, so asto face the pinion 19. The pinion brake apparatus 20 adjusts africtional force of a gear of the pinion 19. More specifically, when thefrictional force is maximized, the pinion brake apparatus 20 prohibits(forbids) the pinion 19 from rotating relative to the central pin 6 (thevehicle body 2). When the frictional force is minimized (when thefrictional force is set to zero, or the pinion 19 is released), thepinion brake apparatus 20 allows (frees) the pinion 19 to rotaterelative to the central pin 6 (the vehicle body 2).

The pinion brake apparatus 20 can be configured to, for example, includean engagement portion (not illustrated) that is frictionally engagedwith the pinion 19. In other words, the pinion brake apparatus 20 can beconfigured to prohibit the pinion 19 from rotating by pressing theengagement portion against the pinion 19 (engaging the engagementportion with the pinion 19) when being in a braking state (a lockingstate) with the frictional force maximized, and allows the pinion 19 torotate by retracting the engagement portion from the pinion 19(disengaging the engagement portion from the pinion 19) when being in anot-braking state (a releasing state) with the frictional forceminimized.

The pinion brake apparatus 20 does not necessarily have to be configuredto use frictional engagement in this manner. In other words, the pinionbrake apparatus 20 can employ any of various kinds of configurations (abrake configuration and a lock configuration), such as a configurationusing friction, a configuration using a pin (engagement), and aconfiguration using a hydraulic pressure, as long as this configurationcan acquire a required resistance force (a frictional force).

As illustrated in FIG. 8, the pinion brake apparatus 20 is connected tothe controller 23 that will be described below, and is switched betweenthe braking state (the locking state) and the not-braking state (thereleasing state) according to an instruction signal (a control signal)from the controller 23. For example, the pinion brake apparatus 20 isswitched to the braking state (the locking state) according to aninstruction (a signal) from the controller 23 when the railway vehicle 1is in the safe mode 1 illustrated in FIGS. 5(D) and 6(D) that will bedescribed below. In this case, the attenuation damper 13 and theelectric damper 14 are connected in parallel, and it is possible torealize the operation state (the operation mode) using both theattenuation damper 13 and the electric damper 14.

On the other hand, when the railway vehicle 1 is in the normal operationmode illustrated in FIGS. 5(B) and 6(B) or in the safe mode 2illustrated in FIGS. 5(C) and 6(C), the pinion brake apparatus 20 isswitched to the not-braking state (the releasing state) according to aninstruction (a signal) from the controller 23, thereby allowing thepinion 19 to rotate around the central pin 6. In this case, theattenuation damper 13 and the electric damper 14 are mechanicallyconnected in series. Then, when the attenuation damper 13 and theelectric damper 14 are connected in series in this manner, fixing one ofthe attenuation damper 13 and the electric damper 14 (prohibiting theone from extending or compressing) can realize the operation state (theoperation mode) using the other of the attenuation damper 13 and theelectric damper 14 alone. For example, setting the attenuation damperlock apparatus 13G into the locking state can realize the operation modeusing the electric damper 14 alone, i.e., the normal operation modeillustrated in FIGS. 5(B) and 6(B).

Next, an operation principle of the damper apparatus 12 will bedescribed with reference to FIGS. 6(A) to (D). In FIGS. 6(A) to (D), theattenuation damper 13 and the electric damper 14 are illustrated as ifthey are arranged so as to have same extension and compressiondirections for facilitating better understanding of operations of therespective constituent members of the damper apparatus 12. Further, therod 13B of the attenuation damper 13 and the movable element 14B of theelectric damper 14 are schematically illustrated as if the racks 17 and18 (the tooth portions 17A and 18B) are directly formed thereon in sucha manner that the racks 17 and 18 face each other. Further, in FIGS.6(A) to (D), a member corresponding to the central pin 6 illustrated inFIGS. 1 to 5, i.e., a member (a vehicle body coupling member) connecting(coupling) the vehicle body 2 and the pinion 9 to each other isillustrated as a rod-like member (a rod member).

A black triangle X1 illustrated in FIG. 6(B) indicates that the rod 13Bis locked (fixed) by the attenuation damper lock apparatus 13G. A blacktriangle X2 illustrated in FIG. 6(C) indicates that the movable element14B is locked (stuck or fixed) due to a malfunction of the electricdamper 14 or by the electric damper lock apparatus provided asnecessary. A black triangle X3 illustrated in FIG. 6(D) indicates thatthe pinion 19 is prohibited (locked) from rotating by the pinion brakeapparatus 20.

FIG. 6(A) illustrates a neutral state (a neutral position and an initialposition). This case corresponds to, for example, such a state that allof the attenuation damper lock apparatus 13G, the pinion brake apparatus20, and the electric damper lock apparatus provided as necessary unlock(or lock) their respective targets.

FIG. 6(B) illustrates the normal operation mode, i.e., an activeoperation in which the attenuation damper lock apparatus 13G locks(fixes) the attenuation damper 13, and the pinion brake apparatus 20(and the electric damper lock apparatus provided as necessary) unlocksthe pinion 19 (and the electric damper 14). In this state, a relativedisplacement between the cylinder 13A and the rod 13B of the attenuationdamper 13 is limited (prohibited) (the rod 13B is fixed relative to thebogie 5), while a relative displacement between the stator 14A and themovable element 14B of the electric damper 14, and a rotation of thepinion 19 are not limited (not prohibited).

In this case, when the central pin 6 (the pinion 19) is displaced(vibrates) together with the vehicle body 2 in the left-right direction(a vertical direction in FIGS. 6(A) to (D)) of the vehicle body 2 due toan input from the vehicle body side, the pinion 19 meshed with the rack18 (the tooth portion 18A) of the rod 13B is displaced in the left-rightdirection of the vehicle body 2 (the vertical direction illustrated inFIGS. 6(A) to (D)) while rotating along the rack 18 (the tooth portion18A) of the rod 13B based on this meshed engagement since a displacementof the rod 13B of the attenuation damper 13 is limited. At the sametime, since the pinion 19 is also meshed with the rack 17 (the toothportion 17A) of the stator 14A of the electric damper 14, the stator 14Ais displaced by a displacement amount twice a displacement amount of thepinion 19 in the same direction as a displacement direction of thepinion 19 according to the displacement of the pinion 19 in theleft-right direction (the vertical direction illustrated in FIGS. 6(A)to (D)).

At this time, the attenuation damper 13 is locked, whereby theattenuation damper 13 does not function to cancel out the movement ofthe electric damper 14 (does not interfere with the movement of theelectric damper 14). Therefore, a force generated by the electric damper14 is efficiently transmitted to the central pin 6 (the vehicle body 2).Further, a speed reduction mechanism (a reducer) is constructed betweenthe pinion 39 and the racks 17 and 38, whereby a force twice the forcegenerated by the electric damper 14 is transmitted to the central pin 6(the vehicle body 2).

FIG. 6(C) illustrates the safe mode 2, i.e., a passive operation inwhich the attenuation damper lock apparatus 13G and the pinion brakeapparatus 20 unlock the attenuation damper 13 and the pinion 19,respectively, and the electric damper 14 is locked (stuck or fixed) dueto a malfunction of the electric damper 14 or by the electric damperlock apparatus provided as necessary. In this state, a relativedisplacement between the stator 14A and the movable element 14B of theelectric damper 14 is limited (prohibited), while a relativedisplacement between the cylinder 13A and the rod 13B of the attenuationdamper 13, and a rotation of the pinion 19 are not limited (notprohibited).

In this case, when the central pin 6 (the pinion 19) is displaced(vibrates) together with the vehicle body 2 in the left-right direction(the vertical direction in FIGS. 6(A) to (D)) of the vehicle body 2 dueto an input from the vehicle body side, the pinion 19 meshed with therack 17 (the tooth portion 17A) of the movable element 14B is displacedin the left-right direction of the vehicle body 2 (the verticaldirection illustrated in FIGS. 6(A) to (D)) while rotating along therack 17 (the tooth portion 17A) of the movable element 14B based on thismeshed engagement since a displacement of the movable element 14B of theelectric damper 14 is limited. At the same time, since the pinion 19 isalso meshed with the rack 18 (the tooth portion 18A) of the rod 13B ofthe attenuation damper 13, the rod 13B is displaced by a displacementamount twice a displacement amount of the pinion 19 in the samedirection as a displacement direction of the pinion 19 according to thedisplacement of the pinion 19 in the left-right direction (the verticaldirection illustrated in FIGS. 6(A) to (D)).

At this time, since the electric damper 14 does not work, the movementof the central pin 6 (the vehicle body 2) (=the movement of the pinion19) is absorbed by the attenuation damper 13. In this case, the speedreduction mechanism (the reducer) is constructed between the pinion 19and the racks 17 and 18, whereby a force from the central pin 6 (thevehicle body 2) is transmitted to the attenuation damper 13 while beingreduced to half.

FIG. 6(D) illustrates the safe mode 1, i.e., a parallel operation inwhich the attenuation damper lock apparatus 13G (and the electric damperlock apparatus provided when necessary) unlocks the attenuation damper13 (and the electric damper 14), and the pinion brake apparatus 20 locksthe pinion 19. In this state, a rotation of the pinion 19 is limited(prohibited), while a relative displacement between the stator 14A andthe movable element 14B of the electric damper 14 and a relativedisplacement between the cylinder 13A and the rod 13B of the attenuationdamper 13 are not limited.

In this case, when the central pin 6 (the pinion 19) is displaced(vibrates) together with the vehicle body 2 in the left-right direction(the vertical direction in FIGS. 6(A) to (D)) of the vehicle body 2 dueto an input from the vehicle body side, the movable element 14B of theelectric damper 14 and the rod 13B of the attenuation damper 13 aredisplaced by the same displacement amounts as a displacement amount ofthe pinion 19 in the same direction as a displacement direction of thepinion 19 according to the displacement of the pinion 19 in theleft-right direction (the vertical direction illustrated in FIGS. 6(A)to (D)), since the rack 17 (the tooth portion 17A) of the movableelement 14B of the electric damper and the rack 18 (the tooth portion18B) of the rod 13B of the attenuation damper 13 are meshed with thepinion 19, and a rotation of the pinion 19 is limited (prohibited).

Next, the operation of the damper apparatus 12 will be described withuse of variables defined in FIG. 7. In FIG. 7, the electric damper 14 isexpressed as a fluid pressure shock absorber having a dampingcoefficient C1, and the attenuation damper 13 is expressed as a fluidpressure shock absorber having a damping coefficient C2 forsimplification. Further, in FIG. 7, the member corresponding to thecentral pin 6 illustrated in FIGS. 1 to 5, i.e., the member (the vehiclebody coupling member) connecting (coupling) the vehicle body 2 and thepinion 19 to each other is illustrated as a rod-like member (a rodmember), in a similar manner to FIGS. 6(A) to (D).

The respective variables (parameters) illustrated in FIG. 7 are asfollows. Directions indicated by arrows illustrated in FIG. 7 indicatedirections of the respective variables.

v₁: a movement speed of the movable element 14B of the electric damper14 [m/s]F₁: the force generated by the movable element 14B of the electricdamper 14 [N]v₂: a movement speed of the rod 13B of the attenuation damper 13 [m/s]F₂: the force generated by the rod 13B of the attenuation damper 13 [N]ω: an angular speed of the pinion 19 [rad/s]r: a radius of the pinion 19 [m]T_(r): a braking torque of the pinion 19 [N·m]F_(r): a braking force at a portion where the pinion 19 is meshed witheach of the racks 17 and 18 (a contact point therebetween) [N]C_(r): an equivalent rotational damping coefficient of the pinion 19[N·m/rad/s]v: a movement speed of the rod member (the central pin 6 and the vehiclebody 2) ([m/s]F: a force generated by the rod member (the central pin 6 and thevehicle body 2) [N]

In this case, relationships expressed by the following equations,equations 1 and 2, are established among the forces of the movableelement 14B of the electric damper 14, the rod 13B of the attenuationdamper 13, and the central pin 4 (the vehicle body 2), and the speeds ofthe movable element 14B of the electric damper 14, the rod 13B of theattenuation damper 13, and the central pin 4 (the vehicle body 2),respectively.

$\begin{matrix}{F = {F_{1} + F_{2}}} & \left\lbrack {{EQUATION}\mspace{14mu} 1} \right\rbrack \\{v = {\frac{1}{2}\left( {v_{1} + v_{2}} \right)}} & \left\lbrack {{EQUATION}\mspace{14mu} 2} \right\rbrack\end{matrix}$

Regarding the rotational direction of the pinion 19, relationshipsexpressed by the following equations, equations 3 and 4 are established.

$\begin{matrix}{\omega = \frac{v_{1} - v_{2}}{r}} & \left\lbrack {{EQUATION}\mspace{14mu} 3} \right\rbrack \\{T_{r} = {{2\; r\; F_{r}} = {C_{r}\omega}}} & \left\lbrack {{EQUATION}\mspace{14mu} 4} \right\rbrack\end{matrix}$

From the equations 3 and 4, the braking force F_(r) at the portion wherethe pinion 19 is meshed with each of the racks 17 and 18 (the contactpoint) can be expressed by the following equation, an equation 5,assuming that the pinion 19 corresponds to a rotational damper.

$\begin{matrix}{F_{r} = {C_{r}\frac{v_{1} - v_{2}}{2\; r^{2}}}} & \left\lbrack {{EQUATION}\mspace{14mu} 5} \right\rbrack\end{matrix}$

If C₀ [N/m/s] is defined to represent an equivalent damping coefficientof the pinion 19 in a linear direction while C_(r) is defined torepresent the equivalent damping coefficient of the pinion 19 in therotational direction, a relationship expressed by the followingequation, an equation 6 is established therebetween.

$\begin{matrix}{C_{0} = \frac{C_{r}}{r^{2}}} & \left\lbrack {{EQUATION}\mspace{14mu} 6} \right\rbrack\end{matrix}$

In this case, the braking force F_(r) at the portion where the pinion 19is meshed with each of the racks 17 and 18 (the contact point) isexpressed by the following equation, an equation 7 with use of only thevariables for the linear direction.

$\begin{matrix}{F_{r} = {\frac{C_{0}}{2}\left( {v_{1} - v_{2}} \right)}} & \left\lbrack {{EQUATION}\mspace{14mu} 7} \right\rbrack\end{matrix}$

Further, the force (the thrust force) generated by the electric damper14 and the force (the damping force or the absorbing force) generated bythe attenuation damper 13 are expressed by the following equations,equations 8 and 9 according to an equation for a balance between forces,respectively.

F ₁ −F _(r) =C ₁ v ₁  [EQUATION 8]

F ₁ −F _(r) =C ₂ v ₂  [EQUATION 9]

With use of these equations, a work of the electric damper 14, theattenuation damper 13, and the pinion 19 is expressed by the followingequation, an equation 10 according to the law of the conservation ofenergy.

(F ₁ −F _(r))v ₁+(F ₂ +F _(r))v ₂ +T _(j) ω=Fv  [EQUATION 10]

The left side of the equation 10 can be converted in the followingmanner.

On the other hand, the right side of the equation 10 can be converted inthe following manner.

Since the left side=the right side, i.e., the equation 11=the equation12, the equation 10 can be converted in the following manner.

$\begin{matrix}{{{{\left( {C_{1} + C_{0}} \right)v_{1}^{2}} - {2\; C_{0}v_{1}v_{2}} + {\left( {C_{2} + C_{0}} \right)v_{2}^{2}}} = {\frac{1}{2}\left( {{C_{1}v_{1}^{2}} + {\left( {C_{1} + C_{2}} \right)v_{1}v_{2}} + {C_{2}v_{2}^{2}}} \right)}}{{{\left( {C_{1} + {2\; C_{0}}} \right)v_{1}^{2}} - {\left( {C_{1} + C_{2} + {4\; C_{0}}} \right)v_{1}v_{2}} + {\left( {C_{2} + {2\; C_{0}}} \right)v_{2}^{2}}} = 0}} & \left\lbrack {{EQUATION}\mspace{14mu} 13} \right\rbrack\end{matrix}$  (v₁ − v₂)((C₁ + 2 C₀)v₁ − (C₂ + 2 C₀)v_(2 )) = 0

Therefore, when the equation 13 is satisfied, a relationship expressedby the following equation, an equation 14 or 15 can be establishedbetween v₁ and v₂.

$\begin{matrix}{v_{1} = v_{2}} & \left\lbrack {{EQUATION}\mspace{14mu} 14} \right\rbrack \\{v_{1} = {\frac{C_{2} + {2\; C_{0}}}{C_{1} + {2\; C_{0}}}v_{2}}} & \left\lbrack {{EQUATION}\mspace{14mu} 15} \right\rbrack\end{matrix}$

According to the equation 14, the pinion 19 is non-rotational, and thefollowing equation, an equation 16 is established. This means that theelectric damper 14 and the attenuation damper 13 are connected inparallel. In other words, the damper apparatus 12 can be considered as aparallel mechanism.

F=F ₁ +F ₂ ,v=v ₁ =v ₂  [EQUATION 16]

According to the equation 15, the pinion 19 is rotational, and thefollowing equation, an equation 17 is established.

v ₁ +v ₂=2v  [EQUATION 17]

According to the equation 15, v₁ is expressed by an equation 18, and v₂is expressed by an equation 19.

$\begin{matrix}{v_{1} = {\frac{2\left( {C_{2} + {2\; C_{0}}} \right)}{C_{1} + C_{2} + {4\; C_{0}}}v}} & \left\lbrack {{EQUATION}\mspace{14mu} 18} \right\rbrack \\{v_{2} = {\frac{2\left( {C_{1} + {2\; C_{0}}} \right)}{C_{1} + C_{2} + {4\; C_{0}}}v}} & \left\lbrack {{EQUATION}\mspace{14mu} 19} \right\rbrack\end{matrix}$

Then, Fv can be expressed by an equation 20 according to the law of theconservation of energy, i.e., the equations 11 and 12

$\begin{matrix}\begin{matrix}{{Fv} = {{C_{1}v_{1}^{2}} + {C_{2}v_{2}^{2}} + {C_{0}\; \left( {v_{1} - v_{2}} \right)^{2}}}} \\{= {\frac{\begin{matrix}{{C_{1}\left( {C_{2} + {2\; C_{0}}} \right)}^{2} +} \\{{C_{2}\left( {C_{1} + {2\; C_{0}}} \right)}^{2} + {C_{0}\left( {C_{1} - C_{2}} \right)}^{2}}\end{matrix}}{\left( {C_{1} + C_{2} + {4\; C_{0}}} \right)^{2}}4\; v^{2}}} \\{= {\frac{4\left( {C_{1} + C_{2} + {4\; C_{0}}} \right)\left( {{C_{1}C_{2}} + {C_{1}C_{0\;}} + {C_{2}C_{0}}} \right)}{\left( {C_{1} + C_{2} + {4\; C_{0}}} \right)^{2}}v^{2}}} \\{= {4\frac{{C_{1}C_{2}} + {C_{1}C_{0}} + {C_{2}C_{0}}}{C_{1} + C_{2} + {4\; C_{0}}}v^{2}}}\end{matrix} & \left\lbrack {{EQUATION}\mspace{14mu} 20} \right\rbrack\end{matrix}$

Then, if a composite damping coefficient is expressed by the followingequation, an equation 21 assuming that C represents the compositedamping coefficient, Fv is expressed by an equation 22.

$\begin{matrix}{C = {4\frac{{C_{1}C_{2}} + {C_{1}C_{0}} + {C_{2}C_{0}}}{C_{1} + C_{2} + {4\; C_{0}}}}} & \left\lbrack {{EQUATION}\mspace{14mu} 21} \right\rbrack \\{{Fv} = {Cv}^{2}} & \left\lbrack {{EQUATION}\mspace{14mu} 22} \right\rbrack\end{matrix}$

The composite damping coefficient C is an apparent damping coefficientof the damper apparatus 12 according to the present embodiment.According to the above-described equations, when C₀=0, the compositedamping coefficient C of the equation 21 has a value expressed by thefollowing equation, an equation 23

$\begin{matrix}{C = \frac{4\; C_{1}C_{2}}{C_{1} + C_{2}}} & \left\lbrack {{EQUATION}\mspace{14mu} 23} \right\rbrack\end{matrix}$

In other words, when C₀=0, this state is equivalent to the electricdamper 14 and the attenuation damper 13 being connected in series. Onthe other hand, when C₀=∞, the composite damping coefficient C of theequation 21 has a value expressed by the following equation, an equation24.

$\begin{matrix}\begin{matrix}{C = {4\frac{{C_{1}C_{2}} + {C_{1}C_{0}} + {C_{2}C_{0}}}{C_{1} + C_{2} + {4\; C_{0}}}}} \\{= {\frac{\begin{matrix}{C_{1}^{2} + C_{2}^{2} + {2\; C_{1}^{2}C_{2}} +} \\{{4\; C_{1}C_{0}} + {4\; C_{2}C_{0}}}\end{matrix}}{C_{1} + C_{2} + {4\; C_{0}}} - \frac{C_{1}^{2} - {2\; C_{1}C_{2}} + C_{2}^{2}}{C_{1} + C_{2} + {4\; C_{0}}}}} \\{= {\frac{\left( {C_{1} + C_{2}} \right)\left( {C_{1} + C_{2} + {4\; C_{0}}} \right)}{C_{1} + C_{2} + {4\; C_{0}}} - \frac{C_{1}^{2} - {2\; C_{1}C_{2}} + C_{2}^{2}}{C_{1} + C_{2} + {4\; C_{0}}}}} \\{= {C_{1} + C_{2} - \frac{C_{1}^{2} - {2\; C_{1}C_{2}} + C_{2}^{2}}{C_{1} + C_{2} + {4\; C_{0}}}}}\end{matrix} & \left\lbrack {{EQUATION}\mspace{14mu} 24} \right\rbrack\end{matrix}$

Therefore, when C₀=∞, the composite damping coefficient C of theequation 21 has a value expressed by the following equation, an equation25.

C=C ₁ +C ₂  [EQUATION 25]

In other words, when C₀=∞, this state is equivalent to the electricdamper 14 and the attenuation damper 13 being connected in parallel.Further, when 0<C₀<∞, the composite damping coefficient C has a valueexpressed by the equation 21, and this is an intermediate state betweenthe parallel connection and the series connection. The above descriptionreveals that the damper apparatus 12 according to the present embodimentis configured to be able to mechanically switch the two active andpassive dampers (the force generation units) between the seriesconnection and the parallel connection.

Then, when the railway vehicle 1 is in the normal operation modeillustrated in FIG. 6(B) (during the active operation), C₀=0 and C₂=∞,whereby the equation 23 is converted into the following equation, anequation 26.

$\begin{matrix}\begin{matrix}{C = {4\; {C_{1}\left( \frac{C_{2}}{C_{1} + C_{2}} \right)}}} \\{= {4\; {C_{1}\left( {\frac{C_{1} + C_{2}}{C_{1} + C_{2}} - \frac{C_{1}}{C_{1} + C_{2}}} \right)}}} \\{= {{4\; C_{1}} - \left( \frac{4\; C_{1}^{2}}{C_{1} + C_{2}} \right)}}\end{matrix} & \left\lbrack {{EQUATION}\mspace{14mu} 26} \right\rbrack\end{matrix}$

At this time, since C₂=∞, C is expressed by the following equation, anequation 27.

C=4C ₁  [EQUATION 27]

Further, when the railway vehicle 1 is in the normal operation modeillustrated in FIG. 6(B) (during the active operation), v₂=0, wherebythe equation 17 is converted into the following equation, an equation28.

v ₁=2v  [EQUATION 28]

Therefore, F is expressed by the following equation, an equation 29.

$\begin{matrix}\begin{matrix}{F = {Cv}} \\{= {4\; C_{1}v}} \\{= {2\; C_{1}v_{1}}} \\{= {2\; F_{1}}}\end{matrix} & \left\lbrack {{EQUATION}\mspace{14mu} 29} \right\rbrack\end{matrix}$

In other words, when the railway vehicle 1 is in the normal operationmode (during the active operation), the damper apparatus 12 as a wholeexerts the thrust force F twice the thrust force F₁ of the electricdamper 14.

Similarly, when the railway vehicle 1 is in the safe mode 2 illustratedin FIG. 6(C) (during the passive operation), the damper apparatus 12 asa whole also exerts the thrust force F twice the thrust force F₂ of theattenuation damper 13. In this case, the attenuation damper 13 accordingto the present embodiment should have a damping coefficientcorresponding to one-fourth compared to a conventional attenuationdamper used alone according to C=4C₂, to cause the damper apparatus 12as a whole to exert a damping force similar to a configuration using theconventional attenuation damper alone. The parallel operationillustrated in FIG. 6(D) is as indicated by the equation 16.

Next, the switched states of the damper apparatus 12 will be describedin correspondence with the operation states (the operation modes) of therailway vehicle 1 with reference to FIGS. 4 and 5. In FIGS. 4 and 5, therod 13B of the attenuation damper 13 and the movable element 14B of theelectric damper 14 are schematically illustrated as if the racks 17 and18 (the tooth portions 17A and 18B) are directly formed thereon forfacilitating better understanding of the operations of the respectiveportions of the vehicle body 2, the bogie 5, and the damper apparatus12. Further, black triangles X1, X2, and X3 illustrated in FIGS. 5(A) to(D) indicate that a displacement of the rod 13B, a displacement of themovable element 14B, and a rotation of the pinion 19 are prohibited(forbidden) in a similar manner to FIGS. 6(A) to (D).

FIG. 5(A) corresponds to FIG. 6(A), and illustrates the neutral state(the initial position and the neutral position). This state correspondsto, for example, such a state that all of the rod 13B, the movableelement 14B, and the pinion 19 are unlocked (or all of them are locked).

FIG. 5(B) corresponds to FIG. 6(B), and illustrates the normal operationmode (the active mode) in which a vibration between the vehicle body 2and the bogie 5 is damped only by the electric damper 14 alone. In thismode, the attenuation damper lock apparatus 13G locks (fixes) theattenuation damper 13, and the pinion brake apparatus 20 unlocks thepinion 19.

In this case, when the vehicle body 2 and the bogie 5 are relativelydisplaced in the left-right direction due to an aerodynamic disturbanceonto the vehicle body 2 while the railway vehicle 1 is running, a swayof the vehicle body 2 while the railway vehicle 1 is running on a curve,a sway of the bogie 5 due to a distortion of a track (the rail 4), orthe like, the pinion 19 is displaced in the left-right direction of thevehicle body 2 while rotating along the locked rod 13B of theattenuation damper 13. At this time, the pinion 19 is also meshed withthe rack 17 of the movable element 14B of the electric damper 14.Therefore, the movable element 14B controls (damps) a vibration betweenthe vehicle body 2 and the bogie 5 while being displaced by adisplacement amount twice a displacement amount of the vehicle body 2(the pinion 19) in the same direction as a displacement direction of thevehicle body 2 (the pinion 19) according to the relative displacementbetween the vehicle body 2 and the bogie 5, i.e., the displacement ofthe pinion 19 relative to the bogie 5 in the left-right direction. Inthis case, a force twice the force generated by the electric damper 14is applied to between the vehicle body 2 and the bogie 5 as a controlforce (a vibration damping force). Therefore, it is possible to use anelectric damper generating a smaller force as the electric damper 14compared to, for example, a configuration including an electric damperalone.

FIG. 5(C) corresponds to FIG. 6(C), and illustrates the safe mode 2 (thepassive mode) into which the railway vehicle 1 is switched when theelectric damper 14 becomes unable to perform a stroke (extension orcompression) due to a malfunction of the electric damper 14, morespecifically, a jam of the movable element 14B to the stator 14A (themovable element 14B is stuck to the stator 14A). In this mode, both theattenuation damper lock apparatus 13G and the pinion brake apparatus 20unlock (release) the respective targets.

In this case, when the vehicle body 2 and the bogie 5 are relativelydisplaced in the left-right direction due to an aerodynamic disturbanceonto the vehicle body 2 while the railway vehicle 1 is running, a swayof the vehicle body 2 while the railway vehicle 1 is running on a curve,a sway of the bogie 5 due to a distortion of a track (the rail 4), orthe like, the pinion 19 is displaced in the left-right direction whilerotating along the stuck movable element 14B of the electric damper 14.At this time, the pinion 19 is also meshed with the rack 18 of the rod13B of the attenuation damper 13. Therefore, the rod 13B controls(absorbs) a vibration between the vehicle body 2 and the bogie 5 whilebeing displaced by a displacement amount twice a displacement amount ofthe vehicle body 2 (the pinion 19) in the same direction as adisplacement direction of the vehicle body 2 (the pinion 19) accordingto the relative displacement between the vehicle body 2 and the bogie 5,i.e., the displacement of the pinion 19 relative to the bogie 5 in theleft-right direction. In this case, a force twice the force generated bythe attenuation damper 13 is applied to between the vehicle body 2 andthe bogie 5 as an absorption force (the vibration damping force).

FIG. 5(D) corresponds to FIG. 6(D), and illustrates the safe mode 1 (theparallel mode) into which the railway vehicle is switched when thethrust force of the electric damper 14 becomes insufficient due to amalfunction of the electric damper 14, more specifically, due to a stopof energization of the electric damper 14 (a power supply to theelectric damper 14) or the like. In this mode, the pinion brakeapparatus 20 is set into the braking (locking) state, while theattenuation damper lock apparatus 13G unlocks the attenuation damper 13.

In this case, when the vehicle body 2 and the bogie 5 are relativelydisplaced in the left-right direction due to an aerodynamic disturbanceonto the vehicle body 2 while the railway vehicle 1 is running, a swayof the vehicle body 2 while the railway vehicle 1 is running on a curve,a sway of the bogie 5 due to a distortion of a track (the rail 4), orthe like, the movable element 14B of the electric damper 14 and the rod13B of the attenuation damper 13 are displaced by the same displacementamounts as a displacement amount of the pinion 19 in the same directionas a displacement direction of the pinion 19 according to thedisplacement of the pinion 19 in the left-right direction. At this time,it is possible to damp (absorb) a vibration between the vehicle body 2and the bogie 5 by the attenuation damper 13 even with insufficiency ofthe thrust force of the electric damper 14.

In the normal operation mode (the active mode) illustrated in FIG. 5(B)and the safe mode (the passive mode) illustrated in FIG. 5(C), themovable element 14B of the electric damper 14 or the rod 13B of theattenuation damper 13 is displaced by the displacement amount twice thedisplacement amount between the bogie 5 and the vehicle body 2. Forexample, assuming that the railway vehicle 1 is running on a railroadline in operation with a relative displacement of approximately ±20 mmgenerated between the vehicle body 2 and the bogie 5, the movableelement 14B of the electric damper 14 is displaced by approximately ±40mm in the normal operation mode.

Then, a maximum displacement amount of the movable element 14B of theelectric damper 14 is approximately ±100 to 140 mm, in consideration ofa possibility of an input of a large relative displacement i.e., a largerelative displacement of approximately ±50 to 70 mm between the vehiclebody 2 and the bogie 5 when the railway vehicle 1 changes a line (passesthrough a point) in a rail yard or the pneumatic spring 11 is broken(goes flat). Therefore, setting a maximum stroke length (an allowabledisplacement amount) of the electric damper 14 according thereto maylead to an increase in the number of permanent magnets of the electricdamper 14 that are arranged side by side in the axial direction,resulting in a cost increase.

Therefore, a possible solution therefor is to configure the railwayvehicle 1 so as to be switched from the normal operation mode to thesafe mode 1 (the parallel mode) even without a malfunction of theelectric damper 14 (insufficiency of the thrust force), when a largerelative displacement is generated between the vehicle body 2 and thebogie 5, such as the line change in the rail yard or the breakage of thepneumatic spring 11. In this case, i.e., in the safe mode 1 (theparallel mode), the displacement amount of the movable element 14B ofthe electric damper 14 or the displacement amount of the rod 13B of theattenuation damper 13 matches the displacement amount between thevehicle body 2 and the bogie 5, whereby it is possible to reduce themaximum stroke length of the electric damper 14. For example, themaximum stroke length of the electric damper 14 can be set to the samelength (approximately ±50 to 70 mm) as the conventional configuration(the configuration including the electric damper alone).

When the railway vehicle 1 is in the safe mode 2 (the passive mode)illustrated in FIG. 5(C), i.e., when the electric damper 14 becomesunable to perform a stroke due to a jam of the movable element 14B tothe stator 14A (the movable element 14B is stuck to the stator 14A), therailway vehicle 1 may arrive at the rail yard in this state. Inconsideration of this possibility, it is preferable to secure a length(approximately ±100 to 140 mm) twice the conventional configuration (theconfiguration including the attenuation damper alone) as a maximumstroke length (an allowable displacement amount) of the attenuationdamper 13.

Next, an acceleration sensor 21 mounted on the vehicle body 2 and apinion rotational sensor 22 mounted on the gear apparatus 15 will bedescribed.

As illustrated in FIG. 1, the acceleration sensor 21 is mounted on thevehicle body 2 at a position close to the damper apparatus 12. Thisacceleration sensor 21 detects an acceleration (a vehicle bodyleft-right acceleration) of a vibration of the vehicle body 2 in theleft-right direction on the vehicle body side, which corresponds to thesprung side of the railway vehicle 1, and outputs a signal from thisdetection to the controller 23 that will be described below. Forexample, the acceleration sensor 21 is mounted for each of the bogies 5in correspondence of each of the bogies 5 disposed on the both sides ofthe vehicle body 2 in the front-back direction, whereby the railwayvehicle 1 is configured to include two acceleration sensors 21 in totalfor each vehicle (for each vehicle body).

As illustrated in FIG. 2, the pinion rotational sensor 22 is mounted onthe gear case 16 of the gear apparatus 15 at, for example, a positionfacing the pinion 19. This pinion rotational sensor 22 detects arotation of the pinion 19, and outputs a signal from this detection tothe controller 23 that will be described below.

Next, the controller 23, which controls the damper apparatus 12, i.e.,controls damping of a vibration between the vehicle body 2 and the bogie5 (controls an output of the electric damper 14) and controls switchingof the gear apparatus 15, will be described.

The reference numeral 23 denotes the controller including amicrocomputer or the like, and this controller 23 determines anoperation state, a malfunction state, and the like of the railwayvehicle 1 to switch the damper apparatus 12, and adjusts the thrustforce of the electric damper 14 so as to reduce a vibration of thevehicle body 2 in the left-right direction. An input side of thecontroller 23 is connected to the acceleration sensor 21, the pinionrotational sensor 22, the electric damper 14, and the like, and anoutput side of the controller 23 is connected to the electric damper 14,the attenuation damper lock apparatus 13G, the pinion brake apparatus20, and the like. The controller 23 includes a memory (not illustrated)realized by a ROM, a RAM, or the like, and this memory stores aprocessing program used by a vibration control unit 29 illustrated inFIG. 8 (a processing program executed in step 15 illustrated in FIG.10), a processing program used by a mode switching determination unit 32illustrated in FIG. 8 (a processing program illustrated in FIGS. 9 to14), a threshold value used in a determination about mode switching, andthe like.

As illustrated in FIG. 8, the controller 23 includes a vehicle bodyleft-right acceleration input unit 24, an electric damper displacementinput unit 25, an electric damper current input unit 26, a pinionrotational angle input unit 27, a vehicle positional informationacquisition unit 28, the vibration control unit 29, a current controlunit 30, an electric damper current output unit 31, the mode switchingdetermination unit 32, an attenuation damper lock apparatus signaloutput unit 33, a pinion brake apparatus signal output unit 34, and thelike.

The vehicle body left-right acceleration input unit 24 is connected tothe acceleration sensor 21, and an acceleration of the vehicle body 2 inthe left-right direction is input from this acceleration sensor 21 tothe vehicle body left-right acceleration input unit 24. The electricdamper displacement input unit 25 is connected to the electric damper14, and a displacement (a stroke amount or an extension/compressionamount) of the movable element 14B is input from this electric damper 14into the electric damper displacement input unit 25. The electric dampercurrent input unit 26 is connected to a UVW line (not illustrate) of theelectric damper 14, and a current value to be supplied from a currentoutput circuit into the electric damper 14 is input into the electricdamper current input unit 26. The pinion rotational angle input unit 27is connected to the pinion rotational sensor 22, and a displacement (arotational speed or a rotational angle) of the pinion 19 is input intothe pinion rotational angle input unit 27.

The acceleration of the vehicle body 2 in the left-right direction isinput from the vehicle body left-right acceleration input unit 24 intothe vibration control unit 29, and the vibration control unit 29calculates a thrust force instruction value corresponding to a forcethat the electric damper 14 should generated based on this acceleration.For example, the vibration control unit 29 calculates the thrust forceinstruction value according to the Skyhook control law, the LQG controllaw, H∞ control law, or the like. The current control unit 30 outputs acurrent instruction for controlling a current to be supplied to theelectric damper 14 based on the thrust force instruction value from thevibration control unit 29, an electric angle calculated from thedisplacement of the electric damper 14 acquired from the electric damperdisplacement input unit 25, and the UVW-phase current value from theelectric damper current input unit 26. The electric damper currentoutput unit 31 actuates the current output circuit of the electricdamper 14 based on the current instruction from the current control unit30.

The mode switching determination unit 32 determines which mode should beselected as the switched state (the operation mode) of the damperapparatus 12, the normal operation mode, the safe mode 1, or the safemode 2, based on the displacement (the rotational angle) of the pinion19 that is acquired from the pinion rotational angle input unit 27,positional information of the vehicle 1 that is acquired from thevehicle position information acquisition unit 28, the displacement ofthe electric damper 14 that is acquired from the electric damperdisplacement input unit 25, and the current value acquired from theelectric damper current input unit 26. Then, the mode switchingdetermination unit 32 outputs a signal for locking the attenuationdamper 13, a signal for unlocking the pinion 19, and the like accordingto the determined mode.

The attenuation damper lock apparatus signal output unit 33 outputs alock signal (or a release signal) to the attenuation damper lockapparatus 13G based on the signal from the mode switching determinationunit 32. The pinion brake apparatus signal output unit 34 outputs abrake release signal (or a brake application signal) to the pinion brakeapparatus 20 based on the signal from the mode switching determinationunit 32.

The damper apparatus 12 is set so as to be placed into the parallel mode(the safe mode 1) when power is not supplied to the controller 23 (whena power supply is stopped). In other words, the attenuation damper lockapparatus 13G is configured as a default unlocking apparatus thatunlocks the attenuation damper 13 when power is not supplied (when thecontroller 23 is powered off) while locking the attenuation damper 13when power is supplied (when a signal is input), and the pinion brakeapparatus 20 is configured as a default braking apparatus that brakesthe pinion 19 when power is not supplied (when the controller 23 ispowered off) while releasing the pinion 19 when power is supplied (whena signal is input). Further, the electric damper 14 is placed into afree state that allows the electric damper 14 to freely extend orcompress when power is not supplied (when the controller 23 is poweredoff). Assume that, when the electric damper 14 is set in this manner,the attenuation damper lock apparatus signal output unit 33 outputs alock signal (supplies power) when causing the attenuation damper lockapparatus 13G to lock the attenuation damper 13, and the pinion brakeapparatus signal output unit 34 outputs a brake release signal (suppliespower) when causing the pinion brake apparatus 20 to release the pinion19.

Next, a program for controlling the damper apparatus 12 that is executedby the controller 23 will be described with reference to FIGS. 9 to 14.

First, FIG. 9 illustrates processing of a main flow of the controller23. This main flow is called by a timer interruption or the like foreach cycle during which a control calculation is performed. In the mainflow, first, in step 1, the controller 23 acquires the vehiclepositional information by performing communication processing or thelike. The information acquired by the vehicle positional informationacquisition unit 28 of the controller 23 is used as this vehiclepositional information. In a subsequent step, step 2, the controller 23determines whether a present railroad line is a railroad line thatallows the railway vehicle 1 to shift to the normal operation mode,i.e., the railway vehicle 1 is running on a railroad line in operationwhere the railway vehicle 1 transports passengers or the like, orwhether the railway vehicle 1 is running on a track where an excessivelylarge displacement may be generated between the vehicle body 2 and thebogie 5, such as a line in the rail yard, based on the vehiclepositional information acquired in step 1.

If the controller 23 determines “YES”, i.e., determines that the presentrailroad line is a railroad line that allows the railway vehicle 1 toshift to the normal operation mode in step 2, the processing of the mainflow proceeds to step 3, in which the controller 23 determines what astate flag indicates, i.e., determines which mode the present mode is.If the controller 23 determines that the state flag indicates the normaloperation mode in this step, step 3, the processing of the main flowproceeds to step 4, in which the controller 23 performs processing inthe normal operation mode.

If the controller 23 determines that the state flag indicates the safemode 1 in step 3, the processing of the main flow proceeds to step 5, inwhich the controller 23 performs processing in the safe mode 1. The safemode 1 executed in this step, step 5 corresponds to the safe mode 1 whenthe thrust force of the electric damper 14 becomes insufficient.

If the controller 23 determines that the state flag indicates the safemode 2 in step 3, the processing of the main flow proceeds to step 6, inwhich the controller 23 performs processing in the safe mode 2. The safemode 2 is the mode when the electric damper 14 is stuck (the electricdamper 14 becomes unable to perform a stroke).

The state flag indicating the safe mode 1 is raised only during theprocessing in the normal operation mode. Further, the state flagindicating the safe mode 2 is raised only during the processing in thenormal operation mode or the processing in the safe mode 1. Then, thestate flag according to an initial setting (default) is set to thenormal operation mode. Therefore, after the railway vehicle 1 (thecontroller 23) is powered on, the processing in the normal operationmode is always performed first when the railway vehicle 1 enters arailroad line that allows the railway vehicle 1 to shift to the normaloperation mode.

On the other hand, if the controller 23 determines “NO”, i.e.,determines that the present railroad line is not a railroad line thatallows the railway vehicle 1 to shift to the normal operation mode instep 2, the processing of the main flow proceeds to step 7, in which thecontroller 23 determines whether the state flag indicates the normaloperation mode. If the controller 23 determines “YES”, i.e., determinesthat the state flag indicates the normal operation mode in this step,step 7, the processing of the main flow proceeds to step 8, in which thecontroller 23 performs the processing in the safe mode 1. On the otherhand, if the controller 23 determines “NO”, i.e., determines that thestate flag does not indicates the normal operation mode in step 7, theprocessing of the main flow proceeds to step 3, from which thecontroller 23 performs subsequent processing.

Due to this flow, the railway vehicle 1 can be set into the safe mode 1when the state flag indicates other modes than the safe mode 2, if thecontroller 23 determines that the present railroad line is not arailroad line that allows the railway vehicle 1 to shift to the normaloperation mode (for example, the rail yard). The railway vehicle 1 isset into the safe mode 1 in this manner to, even when a large relativedisplacement is generated between the vehicle body 2 and the bogie 5 dueto the line change in the rail yard (the railway vehicle 1 passesthrough a point) or the like, prevent the electric damper 14 from havinga stroke amount twice this displacement.

Next, FIG. 10 illustrates the processing in the normal operation modethat is performed in step 4. In the normal operation mode, theattenuation damper lock apparatus 13G locks the attenuation damper 13,and the pinion brake apparatus 20 releases the pinion 19 to allow thedamper apparatus 12 to be used in the active state. Then, in the normaloperation mode, the controller 23 performs vibration control and currentcontrol of the electric damper 14, and also performs malfunctiondetermination processing that will be described below.

More specifically, in step 11, the controller 23 determines whether theattenuation damper lock apparatus 13G unlocks the attenuation damper 13,i.e., whether the attenuation damper lock apparatus 13G has been in thereleasing state in an immediately preceding control cycle. If thecontroller 23 determines “YES”, i.e., determines that the attenuationdamper lock apparatus 13G unlocks the attenuation damper 13 in thisstep, step 11, the processing in the normal operation mode proceeds tostep 12. In this case, when the controller 23 actuates the attenuationdamper lock apparatus 13G to lock the attenuation damper 13 from such astate that the attenuation damper 13 and the electric damper 14 operatesin parallel, an excessive force may be applied to the attenuation damperlock apparatus 13G, and an operation range of the electric damper 14 maybe limited, depending on a stroke position and a stroke speed of theattenuation damper 13 at the timing of starting locking the attenuationdamper 13.

Therefore, the following steps are performed to find an appropriatetiming of actuating the attenuation damper lock apparatus 13G to lockthe attenuation damper 13. First, in step 12, the controller 23determines whether a stoke position of the electric damper 14 is locatedclose to a stroke central position (the initial position). Theinformation input into the electric damper displacement input unit 25 isused as the stroke position of the electric damper 34. If the controller23 determines “NO”, i.e., determines that the stroke position of theelectric damper 14 is not located close to the stroke central positionin step 12, the controller 23 refrains from actuating the attenuationdamper lock apparatus 13G to lock the attenuation damper 13, and theprocessing in the normal operation mode returns to a START stepillustrated in FIG. 9 via a RETURN step illustrated in FIG. 10 and aRETURN step illustrated in FIG. 9.

On the other hand, if controller 23 determines “YES”, i.e., determinesthat the stroke position of the electric damper 14 is located close tothe stroke central position in step 12, the processing in the normaloperation mode proceeds to step 13, in which the controller 23determines whether a rotational speed of the pinion 19 is sufficientlyslow (the rotational speed is equal to or lower than a preset thresholdvalue that allows the attenuation damper lock apparatus 13G to startlocking the attenuation damper 13). If the controller 23 determines“NO”, i.e., determines that the rotational speed of the pinion 19 is notsufficiently slow (the rotational speed is fast) in this step, step 13,the controller 23 refrains from actuating the attenuation damper lockapparatus 13G to lock the attenuation damper 13, and the processing inthe normal operation mode returns to the START step illustrated in FIG.9 via the RETURN step illustrated in FIG. 10 and the RETURN stepillustrated in FIG. 9.

If the controller 23 determines “YES”, i.e., determines that therotational speed of the pinion 19 is sufficiently slow in step 13, or ifthe controller 23 determines “NO”, i.e., that the attenuation damperlock apparatus 13G has locked the attenuation damper 13 in step 11, theprocessing in the normal operation mode proceeds to step 14, in whichthe controller 23 actuates the attenuation damper lock apparatus 13G tolock the attenuation damper 13 (continue locking the attenuation damper13), and causes the pinion brake apparatus 20 to release the pinion 19(continue releasing the pinion 19). As a result, the railway vehicle 1is placed into the active operation state illustrated in FIGS. 5(B) and6(B) (or is maintained in the active operation state). In subsequentstep, step 15, the controller 23 performs the vibration control and thecurrent control. More specifically, in step 15, the controller 23calculates the thrust force instruction value corresponding to thethrust force that the electric damper 14 should generate based on thepredetermined control law by the vibration control unit 29, and outputsthe instruction current corresponding to this thrust force to theelectric damper 14 via the current control unit 30 and the electricdamper current output unit 31. As a result, it becomes possible tosecure a ride comfort and running stability of the vehicle.Subsequently, in step 16, the controller 23 performs the malfunctiondetermination processing that will be described below.

Next, FIG. 11 illustrates the processing in the safe mode 1 that isperformed in step 5. In the safe mode 1, the controller 23 causes theattenuation damper lock apparatus 13G to unlock the attenuation damper13, and the pinion brake apparatus 20 to brake (lock) the pinion 19 toallow the damper apparatus 12 to be used in the parallel state. Then, inthe safe mode 1, the controller 23 performs processing for determiningwhether the electric damper 14 is stuck.

In this safe mode 1, when the controller 23 places the pinion brakeapparatus 20 into the braking state (the locking state) from such astate that the attenuation damper 13 and the electric damper 14 areconnected in series (a series connection operation), this may lead toimposition of a limitation onto the operation range of the electricdamper 14 depending on a stroke position and a stroke speed of theelectric damper 14 at a timing of starting locking the pinion 19.Therefore, the following steps are performed to find an appropriatetiming of causing the pinion brake apparatus 20 to start braking(locking) the pinion 19. First, in step 21, the controller 23 determineswhether the stroke position of the electric damper 14 is located closeto the stroke central position (the initial position) of the electricdamper 14 in a similar manner to step 12.

If the controller 23 determines “NO”, i.e., determines that the strokeposition of the electric damper 14 is not located close to the strokecentral position in step 21, the controller 23 refrains from causing thepinion brake apparatus 20 to start braking the pinion 19, and theprocessing in the safe mode 1 returns to the START step illustrated inFIG. 9 via a RETURN step illustrated in FIG. 11 and the RETURN stepillustrated in FIG. 9. On the other hand, if the controller 23determines “YES”, i.e., determines that the stroke position of theelectric damper 14 is located close to the stroke central position instep 21, the processing in the safe mode 1 proceeds to step 22, in whichthe controller 23 determines whether the rotational speed of the pinion19 is sufficiently slow (the rotational speed is equal to or lower thana preset threshold value that allows the pinion brake apparatus 20 tostart braking the pinion 19).

If the controller 23 determines “NO”, i.e., determines that therotational speed of the pinion 19 is not sufficiently slow (therotational speed is fast) in this step, step 22, the controller 23refrains from causing the pinion brake apparatus 20 to start braking thepinion 19, and the processing in the safe mode 1 returns to the STARTstep illustrated in FIG. 9 via the RETURN step illustrated in FIG. 11and the RETURN step illustrated in FIG. 9. On the other hand, if thecontroller 23 determines “YES”, i.e., determines that the rotationalspeed of the pinion 19 is sufficiently slow in step 22, the processingin the safe mode 1 proceeds to step 23, in which the controller 23causes the attenuation damper lock apparatus 13G to unlock theattenuation damper 13 and the pinion brake apparatus 20 to brake thepinion 19. As a result, the railway vehicle 1 is placed into theparallel operation state illustrated in FIGS. 5(D) and 6(D). Then, insubsequent step, step 24, the controller 23 performs the processing fordetermining whether the electric damper 14 is stuck as will be describedbelow.

Next, FIG. 12 illustrates the processing in the safe mode 2 that isperformed in step 6. The safe mode 2 is the safe mode into which therailway vehicle 1 shifts when the electric damper 14 is stuck. In thissafe mode 2, immediately after a shift to the processing in the safemode 2, i.e., in step 31, the controller 23 causes the attenuationdamper lock apparatus 13G to unlock the attenuation damper 13 and thepinion brake apparatus 20 to release the pinion 19 to secure the runningstability of the railway vehicle 1. As a result, the railway vehicle 1is placed into the passive operation state illustrated in FIGS. 5(C) and6(C). In this case, for example, until the electric damper 14 isrepaired in the rail yard, the railway vehicle 1 is maintained in thestate of the safe mode 2.

Next, FIG. 13 illustrates the malfunction determination processing thatis performed in step 16. In the malfunction determination processing,the controller 23 determines a malfunction of the electric damper 14,and sets the state flag according to this malfunction.

Therefore, in step 41, the controller 23 determines whether any changeoccurs in the stroke of the electric damper 14. The information inputinto the electric damper displacement input unit 25 is used as thestroke of the electric damper 14. If the controller 23 determines “YES”,i.e., determines that a change occurs in the stroke of the electricdamper 14 in step 41, the malfunction determination processing proceedsto step 42, in which the controller 23 determines whether a current isflowing through the electric damper 14. The information input into theelectric damper current input unit 26 is used as the current value ofthe electric damper 14. If the controller 23 determines “YES”, i.e.,determines that a current is flowing through the electric damper 14according to the current instruction generated by the current controlunit 30 in step 42, it is considered that there is no malfunction in theelectric damper 14, whereby the malfunction determination processingreturns to the START step illustrated in FIG. 9 via a RETURN stepillustrated in FIG. 13 and the RETURN step illustrated in FIG. 10.

On the other hand, if the controller 23 determines “NO”, i.e., that acurrent is not flowing through the electric damper 14 according to thecurrent instruction generated by the current control unit 30(especially, the current value is insufficient) in step 42, it isconsidered that a current is not supplied to the electric damper 14 sothat the thrust force of the electric damper 14 is insufficient. In thiscase, the malfunction determination processing proceeds to step 43, inwhich the controller 23 sets the state flag to the “safe mode 1”. Then,the malfunction determination processing proceeds to the RETURN step.

Further, if the controller 23 determines “NO”, i.e., determines that nochange occurs in the stroke of the electric damper 14 in step 41, themalfunction determination processing proceeds to step 44, in which thecontroller 23 determines whether any (abnormal) change occurs in theacceleration of the vehicle body 2 in the left-right direction. Theinformation input into the vehicle body left-right acceleration inputunit 24 is used as the acceleration of the vehicle body 2 in theleft-right direction. If the controller 23 determines “YES”, i.e., thatan (abnormal) change occurs in the acceleration of the vehicle body 2 inthe left-right direction in step 44, it is considered that the electricdamper 14 does not perform a stroke so that the vehicle body 2excessively vibrates, i.e., the electric damper 14 is stuck. In thiscase, the malfunction determination processing proceeds to step 45, inwhich the controller 23 sets the state flag to the “safe mode 2”. Then,the malfunction determination processing proceeds to the RETURN step. Onthe other hand, if the controller 23 determines “NO”, i.e., determinesthat no (abnormal) change occurs in the acceleration of the vehicle body2 in the left-right direction in step 44, the malfunction determinationprocessing proceeds to step 42, in which the controller 23 performssubsequent processing.

Next, FIG. 14 illustrates the processing for determining whether theelectric damper 14 is stuck, that is performed in step 24. In theprocessing for determining whether the electric damper 14 is stuck, thecontroller 23 determines whether the electric damper 14 is stuck (orjammed), and sets the state flag according to this determination.

Therefore, in step 51, the controller 23 determines whether any changeoccurs in the stoke of the electric damper 14 in a similar manner tostep 41. If the controller 23 determines “YES”, i.e., determines that achange occurs in the stoke of the electric damper 14 in step 51, it isconsidered that the electric damper 14 is not stuck, so that thisprocessing returns to the START step illustrated in FIG. 9 via a RETURNstep illustrated in FIG. 14, the RETURN step illustrated in FIG. 11, andthe RETURN step illustrated in FIG. 9.

On the other hand, if the controller 23 determines “NO”, i.e.,determines that no change occurs in the stroke of the electric damper 14in step 51, this processing proceeds to step 52, in which the controller23 determines whether any (abnormal) change occurs in the accelerationof the vehicle body 2 in the left-right direction in a similar manner tostep 44. If the controller 23 determines “YES”, i.e., determines that an(abnormal) change occurs in the acceleration of the vehicle body 2 inthe left-right direction in step 52, it is considered that the electricdamper 14 does not perform a stroke so that the vehicle body 2excessively vibrations. In this case, this processing proceeds to step53, in which the controller 23 sets the state flag to the “safe mode 2”.Then this processing proceeds to the RETURN step. On the other hand, ifthe controller 23 determines “NO”, i.e., determines that no (abnormal)change occurs in the acceleration of the vehicle body 2 in theleft-right direction in step S52, this processing proceeds to the RETURNstep illustrated in FIG. 14.

In this manner, the processing illustrated in FIGS. 9 to 14 is designedin such a manner that the railway vehicle 1 is allowed to shift from thenormal operation mode to any of the safe mode 1 and the safe mode 2, butis prohibited from shifting from the safe mode 1 to the normal operationmode or from the safe mode 2 to the normal operation mode (unreturnable)if the state flag is set to the safe mode 1 or the safe mode 2. Further,the processing is designed in such a manner that the railway vehicle 1is allowed to shift from the safe mode 1 to the safe mode 2, but isprohibited from shifting from the safe mode 2 to the safe mode 1(unreturnable). This is because the stuck (jammed) electric damper 14 inthe safe mode 2 is highly necessary to be repaired in the rail yard.

The damper apparatus 12 according to the present embodiment isconfigured in this manner. Next, the operation thereof will bedescribed.

First, in the normal operation mode, the attenuation damper lockapparatus 13G locks (fixes) the attenuation damper 13, while the pinionbrake apparatus 20 releases (unlocks) the pinion 19, so that the railwayvehicle 1 is placed in the active operation state. In this case, whenthe vehicle body 2 vibrates in the left-right direction, the electricdamper 14 outputs a thrust force required to damp the vibration, therebysucceeding in securing the ride comfort and running stability of thevehicle.

On the other hand, when the railway vehicle 1 is running in the railyard, or when the thrust force of the electric damper 14 is insufficientdue to a stop of a power supply to the electric damper 14 or the like,the attenuation damper lock apparatus 13G unlocks the attenuation damper13, while the pinion brake apparatus 20 locks the pinion 16, so that therailway vehicle 1 is placed into the state of the safe mode 1, i.e., theparallel operation state. In this case, when the vehicle body 2 vibratesin the left-right direction, this vibration can be damped by theattenuation damper 13 and the electric damper 14, or the attenuationdamper 13 alone.

Further, when the electric damper 14 is stuck, the attenuation damperlock apparatus 13G unlocks the attenuation damper 13, and the pinionbrake apparatus 20 also unlocks the pinion 19, so that the railwayvehicle 1 is placed into the state of the safe mode 2, i.e., the passiveoperation state.

When the gear apparatus 15 constituted by the pinion 19 and the racks 17and 18 is stuck, for example, when the pinion 19 becomes unable torotate due to an entry of a foreign object into the portions where thepinion 19 is meshed with the racks 17 and 18 or the like, the railwayvehicle 1 can be placed into the state of the safe mode 1 (the paralleloperation). More specifically, when the gear apparatus 15 is stuck, thepinion 19 is prohibited (locked) from rotating by the pinion brakeapparatus 20 while the attenuation damper 13 is allowed to be relativelydisplaced, by which a displacement between the vehicle body 2 and thebogie 5 can be absorbed by the attenuation damper 13 and the electricdamper 14.

In this manner, according to the present embodiment, even withinsufficiency of the thrust force of the electric damper 14 oroccurrence of such a malfunction that the electric damper 14 is stuck,and further, even with occurrence of such a malfunction that the gearapparatus 15 is stuck, the railway vehicle 1 can operate in the safemode 1 or the safe mode 2, thereby improving a fail-safe performance.

One possible measure for securing the fail-safe performance against amalfunction of a failure in a power supply that is a stop of a powersupply to an electric damper during an operation is to configure adamper apparatus to include both an electric damper and an attenuationdamper. However, only connecting the electric damper and the attenuationdamper in parallel may lead to the attenuation damper operating so as tocancel out a force generated by the electric damper during a normaloperation.

On the other hand, an electric damper including a rotation-linear motionconversion mechanism (a reducer mechanism) using a ball screw or aroller screw can prevent the damping force from becoming zero at amalfunction of a failure in a power supply, because, for example, aresistance for rotating an electric motor via the reducer mechanismserves as the damping force. However, without any measure taken, theride comfort and the running stability may be reduced, for example, whenthe reducer mechanism is stuck. Therefore, a possible solution thereforis to configure a damper apparatus to include an attenuation dampermounted in series with the electric damper having the rotation-linearmotion conversion mechanism (the reducer mechanism). However, in thiscase, the attenuation damper may absorb a displacement of the electricdamper.

On the other hand, according to the present embodiment, the damperapparatus 12 can generate a desired force according to a condition (anoperation condition or a malfunction condition) at that time regardlessof the operation condition and whether the electric damper 14 and thegear apparatus 15 are normal or abnormal. More specifically, the damperapparatus 12 according to the present embodiment can switch theattenuation damper 13 and the electric damper 14 between the seriesconnection and the parallel connection with use of the gear apparatus15.

Therefore, the damper apparatus 12 can generate the desired force withuse of one or both of the attenuation damper 13 and the electric damper14 according to the operation condition and the malfunction condition.More specifically, for example, the damper apparatus 12 can mechanicallyconnect the attenuation damper 13 and the electric damper 14 in seriesby causing the pinion brake apparatus 20 to unlock the pinion 19. Inthis case, the electric damper 14 can be used alone by causing theattenuation damper lock apparatus 13G to lock the attenuation damper 13.Further, for example, the attenuation damper 13 and the electric damper14 can be connected in parallel by causing the pinion brake apparatus 20to lock the pinion 19 (and also causing the attenuation damper lockapparatus 13G to unlock the attenuation damper 13). In this case, aforce can be acquired from both of the attenuation damper 13 and theelectric damper 14 (from the attenuation damper 13 at the time of afailure in a power supply to the electric damper 14).

According to the present embodiment, the gear apparatus 15 as theswitching unit is constituted by the racks 17 and 18 and the pinion 19,whereby the force can be stably transmitted via the gear apparatus 15 inany switched states (the operation modes) of the series connection andthe parallel connection.

According to the present embodiment, the frictional force of the gear ofthe pinion 19 can be changed by the pinion brake apparatus 20, whereby,for example, the switched state can be switched to the series connection(the normal operation mode or the safe mode 2) by setting the frictionalforce to zero (allowing the pinion 19 to rotate freely). On the otherhand, the switched state can be switched to the parallel connection (thesafe mode 1) by maximizing the frictional force (prohibiting the pinion19 from rotating).

According to the present embodiment, the damper apparatus 12 as theforce generation mechanism is configured to be used as the left-rightmovement damper mounted between the vehicle body 2 and the bogie 5,whereby the damper apparatus 12 can stably generate the described forceaccording to the operation condition and the malfunction conditionbetween the vehicle body 2 and the bogie 5 to improve the performance ofthe railway vehicle 1.

According to the present embodiment, the damper apparatus 12 isconfigured in such a manner that the stator 14A of the electric damper14 and the cylinder 13A of the attenuation damper 13 are mounted on thebogie 5 while the movable element 14B of the electric damper 34 and therod 13B of the attenuation damper 13 are mounted on the racks 17 and 18,respectively, and the pinion 19 is further mounted on the vehicle body 2with the respective racks 17 and 18 meshed therewith so as to sandwichthe pinion 19 from a radial direction. Then, the damper apparatus 12 isconfigured so as to include the attenuation damper lock apparatus 13Gthat prohibits a relative displacement between the cylinder 13A and therod 13B of the attenuation damper 13, and the pinion brake apparatus 20that prohibits a rotation of the pinion 19.

Therefore, when the railway vehicle 1 operates normally (when therailway vehicle 1 is normal), the damper apparatus 12 refrains fromprohibiting a rotation of the pinion 19 while prohibiting a relativedisplacement (extension/compression) of the attenuation damper 13 by theattenuation damper lock apparatus 13G, thereby succeeding intransmitting a whole output of the electric damper 14 to the vehiclebody 2 via the rack 17 and the pinion 19. In other words, when therailway vehicle 1 operates normally, it is possible to prevent the forcegenerated by the electric damper 14 from being absorbed by theattenuation damper 13 to secure the performance of the damper apparatus12 as a whole.

Further, when the railway vehicle 1 operates normally, the forcegenerated by the electric damper 14 is transmitted to the vehicle bodyside via the rack 17 and the pinion 19, whereby the force generated bythe electric damper 14 can be transmitted to the vehicle body side whileboosting it. As a result, even if the electric damper 14 is realized byan electric damper that generates a weak force, it is possible toincrease the force generated by the damper apparatus 12 as a whole.

On the other hand, when some malfunction occurs, for example, when thedamping force of the electric damper 14 is insufficient due to a failurein a power supply or the like, the damper apparatus 12 prohibits arotation of the pinion 19 by the pinion brake apparatus 20 whileallowing a relative displacement of the attenuation damper 13, therebysucceeding in absorbing a displacement between vehicle body 2 and thebogie 5 by the attenuation damper 13. As a result, it is possible toprevent the damper apparatus 12 from becoming unable to generate anydamping force as a whole, whereby it is possible to improve thefail-safe performance and the reliability of the damper apparatus 12.

Further, when the electric damper 14 is stuck, the damper apparatus 12allows a rotation of the pinion 19 and a relative displacement of theattenuation damper 13, thereby succeeding in absorbing a displacementbetween the vehicle body 2 and the bogie 5 by the attenuation damper 13.Therefore, it is also possible to improve the fail-safe performance andsecure the reliability of the damper apparatus 12 in terms thereof.

Further, when the gear apparatus 15 constituted by the pinion 19 and theracks 17 and 18 is stuck, for example, when the pinion 19 becomes unableto rotate due to an entry of a foreign object into the portions wherethe pinion 19 is meshed with the racks 17 and 18, or the like, thedamper apparatus 12 prohibits a rotation of the pinion 19 by the pinionbrake apparatus 20 while allowing a relative displacement of theattenuation damper 13, thereby succeeding in absorbing a displacementbetween the vehicle body 2 and the bogie 5 by the attenuation damper 13and the electric damper 14. In this case, the damper apparatus 12 cangenerate a force as the damper apparatus 12 in which the attenuationdamper 13 and the electric damper 14 are connected in parallel.Therefore, it is also possible to improve the fail-safe performance andsecure the reliability of the damper apparatus 12 in terms thereof.

The above-described first embodiment has been described based on theexample configured in such a manner that the stator 14A and the movableelement 14B of the electric damper 14 are provided (mounted) on thebogie 5 and the rack 17, respectively, while the cylinder 13A and therod 13B of the attenuation damper 13 are provided (mounted) on the bogie5 and the rack 18, respectively. However, the first embodiment is notlimited thereto, and may be configured in such a manner that, forexample, the movable element and the stator of the electric damper are(provided) mounted on the bogie side and rack, respectively, while therod and the cylinder of the attenuation damper are (provided) mounted onthe bogie side and rack, respectively. In other words, the firstembodiment can be configured in such a manner that any one of the statorand movable element of the electric damper is mounted on one member (orthe other member) and the other of the stator and the movable element isprovided (mounted) on the rack, while one of the cylinder and the rod ofthe attenuation damper is mounted on the one member (or the othermember) and the other of the cylinder and the rod is provided (mounted)on the rack.

Next, FIGS. 15 and 16(A) to (D) illustrate a second embodiment of thepresent invention. The above-described first embodiment is configured toinclude the racks on the respective electric damper side and attenuationdamper side, and also include the pinion on the vehicle body side. Onthe other hand, the present embodiment is configured to include theracks on the respective electric damper side and the bogie side, andalso include the pinion on the attenuation damper side. In the followingdescription of the present embodiment, similar components to theabove-described first embodiment will be identified by the samereference numerals as the first embodiment, and descriptions thereofwill be omitted.

A damper apparatus 41 according to the present embodiment is mountedbetween the two members, the vehicle body 2 as the one of the relativelymoving members, and the bogie 5 as the other of the relatively movingmembers. The damper apparatus 41 generally includes a pair ofattenuation dampers 42 as the force generation unit, an electric damper43 as the force generation unit, and a gear apparatus 44 as theswitching unit.

Each of the attenuation dampers 42 includes a rod 42B protruding from acylinder 42A, and generates a damping force by converting motion energyof a forward or backward movement of this rod 42B into heat energy, in asimilar manner to the attenuation damper 13 according to theabove-described first embodiment. A proximal end of the cylinder 42A,which corresponds to a bottom side of each of the attenuation dampers42, is attached inside a stator 43A of the electric damper 43 that willbe described below. On the other hand, a pinion 47 included in the gearapparatus 44 that will be described below is disposed at a distal end ofthe rod 42B, which corresponds to a rod side of each of the attenuationdampers 42.

Further, an attenuation damper lock apparatus 42C (refer to FIGS. 16(A)to (D)), which prohibits (forbids) a relative movement between thecylinder 42A and the rod 42B (a forward or backward movement of the rod42B relative to the cylinder 42A), is disposed at the attenuation damper42. This attenuation damper lock apparatus 42C is similar to theattenuation damper lock apparatus 13G according to the above-describedfirst embodiment, and can employ, for example, a configuration thatrealizes the locking state by prohibiting (blocking) a flow of hydraulicfluid in the cylinder 42A.

The electric damper 43 includes the stator 43A and a movable element 43Blinearly movable relative to the stator 43A in a similar manner to theelectric damper 14 according to the above-described first embodiment. Inother words, the electric damper 43 is configured as a three-phaselinear synchronous motor, and generally includes the bottomedcylindrical stator 43A including an armature 43F with coils 43C, 43D,and 43E of U, V, and W phases provided thereon, and the cylindricalmovable element 43B including a plurality of cylindrical permanentmagnets 43G arranged side by side in an axial direction.

A mounting eye 43H for mounting a proximal end of the stator 43A ontothe vehicle body side is provided at the proximal end of the stator 43A.On the other hand, a rack 45 included in the gear apparatus 44 that willbe described below is provided on a radially inner side of the movableelement 43B. Further, for example, a guide pin (not illustrated), whichis slidable relative to the movable element 43B at a position thatprevents interference with the permanent magnets 43G and a tooth portion45A of the rack 45, is disposed at the stator 43A to allow the movableelement 43B and the stator 43A to have a relative displacement(extension/compression) therebetween while being kept coaxial with eachother.

Further, an electric damper lock apparatus 43J (refer to FIGS. 16(A) to(D)), which prohibits (forbids) a relative movement between the stator43A and the movable element 43B (a forward or backward movement of themovable element 43B relative to the stator 43A), is disposed at theelectric damper 43. This electric damper lock apparatus 43J can beconfigured similarly to the electric damper lock apparatus provided inthe above-described first embodiment as necessary. For example, theelectric damper lock apparatus 43J can be configured to be disposed at,for example, the above-described guide pin, and to fix the movableelement 43B to the guide pin when locking the electric damper.

The gear apparatus 44 is disposed between the attenuation damper 42 andthe electric damper 43. The gear apparatus 44 allows the attenuationdamper 42 and the electric damper 43 to be mechanically switched betweenthe series connection and the parallel connection. Therefore, the gearapparatus 44 generally includes the rack (rack gear) 45 that is onerack, a rack (rack gear) 46 that is the other rack, and the pinions(pinion gears) 47 and 47. The one rack 45 and the other rack 46 aredisposed opposite of the pinion 47 from each other.

The one rack 45 is integrally formed at the movable element 43B of theelectric damper 43. In other words, the one rack 45 is constructed byforming the tooth portion 45A configured to be meshed with the pinion 47inside the movable element 43B of the electric damper 43 in a lengthdirection (the axial direction) in such a manner that the pinion 47 andthe tooth portion 45A face each other.

The other rack 46 includes a rod-like rod member 46A, and a toothportion 46B provided on a one-end side of the rod member 46A so as toextend in the length direction (the axial direction) and configured tobe meshed with the pinion 47. Then, a mounting eye 46C for mounting theother rack 46 onto the bogie side is provided on a proximal end of therod member 46A. For example, a bearing (not illustrated) for positioningthe rod member 46A (fixing a position of a center) is disposed betweenthe rod member 46A, and the stator 43A and the attenuation damper 42 soas to allow the rod member 46A (the other rack 46) and the stator 43A ofthe electric damper 43 to have a relative displacement(extension/compression) therebetween while being kept coaxial with eachother.

The pinions 47 and 47 are formed as annular members including the toothportions 47A configured to be meshed with the racks 45 and 46 on outercircumferential sides thereof, and are attached to the distal ends ofthe rods 42B of the attenuation damper 42, respectively. In this case,the respective pinions 47 are rotatably attached to the distal ends ofthe rods 42B via rolling bearings (not illustrated). Axes of therespective pinions 47 as rotational centers are perpendicular to acentral axis of the rod 42B.

The gear apparatus 44 can be configured in such a manner that a pinionbrake apparatus is provided so as to vary frictional forces of gears ofthe pinions 47 (prohibit rotations of the pinions 47) as necessary. Thispinion brake apparatus can be configured similarly to the pinion brakeapparatus 20 according to the above-described first embodiment. Thepinion brake apparatus can create a state illustrated in FIG. 16(D) thatwill be described below, i.e., a state similar to such a state that theracks 45 and 46 and the pinions 47 of the gear apparatus 44 are fixed(stuck) to each other

Next, an operation principle of the damper apparatus 41 will bedescribed with reference to FIGS. 16(A) to (D). FIGS. 16(A) to (D)illustrate the damper apparatus 41 as if it is configured to includeonly the single attenuation damper 42, and the single pinion 47 meshedwith the racks 45 and 46 for facilitating better understanding ofoperations of the respective consistent members of the damper apparatus41. Further, a black triangle X1 illustrated in FIG. 16(B) indicatesthat the rod 42B is locked (fixed) by the attenuation damper lockapparatus 42C. A black triangle X2 illustrated in FIG. 16(C) indicatesthat the movable element 43B is locked (fixed) by the electric damperlock apparatus 43J. A black triangle X3 illustrated in FIG. 16(D)indicates that a rotation of the pinion 47 is locked (stuck or fixed)due to a malfunction of the damper apparatus 41 or by the pinion brakeapparatus provided as necessary.

FIG. 16(A) illustrates the neutral state (the neutral position and theinitial position). This case corresponds to, for example, such a statethat all of the attenuation damper lock apparatus 42C, the electricdamper lock apparatus 43J, and the pinion brake apparatus provided asnecessary unlock (or lock) the respective their targets.

FIG. 16(B) indicates the active operation in which the attenuationdamper lock apparatus 42C locks (fixes) the attenuation damper, whilethe electric damper lock apparatus 43J (and the pinion brake apparatusprovided as necessary) unlocks the electric damper (and the pinion). Inthis state, a relative displacement between the cylinder 42A and the rod42B of the attenuation damper 42 is limited (prohibited), while arelative displacement between the stator 43A and the movable element 43Bof the electric damper 43 and a rotation of the pinion 47 are notlimited (not prohibited).

In this case, when the rack 46 on the bogie side is displaced (vibrates)together with the bogie 5 in the left-right direction (a verticaldirection in FIGS. 16(A) to (D)) of the vehicle body 2 due to an inputfrom the bogie side, the movable element 43B of the electric damper 43is displaced by the same displacement amount as a displacement amount ofthe rack 46 in a reverse direction of a displacement direction of therack 46 via a rotation of the pinion 47 since a displacement of the rod42B of the attenuation damper 42 is limited. At this time, theattenuation damper 42 is locked so that the attenuation damper 42 doesnot function so as to cancel out the movement of the electric damper 43(does not interfere with the movement of the electric damper 43).Therefore, an entire force generated by the electric damper 43 istransmitted to the rack 46 on the bogie side (as the vibration dampingforce). This active operation state can be used as a mode when theelectric damper 43 is determined to have no malfunction (the normaloperation mode). In this case, the ride comfort can be controlled by theelectric damper 43.

FIG. 6(C) illustrates the passive operation in which the attenuationdamper lock apparatus 42C (and the pinion brake apparatus provided asnecessary) unlocks the attenuation damper (and the pinion), while theelectric damper lock apparatus 43J locks (fixes) the electric damper 43.In this state, a relative displacement between the stator 43A and themovable element 43B of the electric damper 43 is limited (prohibited),while a relative displacement between the cylinder 42A and the rod 42Bof the attenuation damper 42, and a rotation of the pinion 47 are notlimited (not prohibited).

In this case, when the rack 46 on the bogie side is displaced (vibrates)together with the bogie 5 in the left-right direction (the verticaldirection in FIGS. 16(A) to (D)) of the bogie 5 due to an input from thebogie side, the pinion 47 is displaced by a displacement amount half (½)a displacement amount of the rack 46 in the same direction as thedisplacement of the rack 46 while rotating since a displacement of themovable element 43B of the electric damper 43 is limited. As a result,the rod 42B of the attenuation damper 42 is displaced by thedisplacement amount half (½) the displacement amount of the rack 46 inthe same direction as the displacement of the rack 46 (the bogie 5).

At this time, the electric damper 43 is locked and therefore does notwork, whereby an entire work input from the rack 46 on the bogie side isabsorbed by the attenuation damper 42. In this case, a speed reductionmechanism (a reducer) is constructed between the pinion 47 and the racks45 and 46, whereby the attenuation damper 42 is displaced by the amounthalf (½) the displacement of the rack 46 on the bogie side, and a halfof a force generated by the attenuation damper 42 is transmitted to therack 46 on the bogie side. Therefore, the attenuation damper 42 includedin the damper apparatus 41 according to the present embodiment cangenerate a damping force equivalent to the attenuation damper used aloneby having a damping coefficient four times as large as the conventionalattenuation damper used alone.

This passive operation state can be used as a mode when the electricdamper 43 is determined to have a malfunction (the safe mode). In thiscase, the ride comfort can be secured by the attenuation damper 42. Theactive operation state and the passive operation state can be switchedaccording to a malfunction of the electric damper 43, and for example,can be further switched arbitrarily (when necessary) even when theelectric damper 43 does not have a malfunction, i.e., when the railwayvehicle operates normally.

FIG. 16(D) illustrates the parallel operation in which the attenuationdamper lock apparatus 42C and the electric damper lock apparatus 43Junlock the attenuation damper and the electric damper, respectively,while a rotation of the pinion 47 is locked (stuck or fixed) due to amalfunction of the gear apparatus 44 or by the pinion brake apparatusprovided as necessary. In this state, a rotation of the pinion 47 islimited (prohibited), while a relative displacement between the stator43A and the movable element 43B of the electric damper 43, and arelative displacement between the cylinder 42A and the rod 42B of theattenuation damper 42 are not limited.

In this case, the movable element 43B of the electric damper 43 and therod 42B of the attenuation damper 42 are displaced by the same amountsin the same direction as a displacement of the rack 46 on the bogieside. As a result, even when the gear apparatus 44 is stuck, the rack 46on the bogie sie can be displaced (performs a stroke), which improvesthe fail-safe performance and the reliability. If the attenuation damper42 has a damping coefficient four times as large as the conventionaldamper used alone as described above to secure the damping force of thedamper apparatus 41 as a whole during the passive operation, the damperapparatus 41 is four times as rigid as the conventional damper usedalone when the force generated by the electric damper 43 is zero duringthe parallel operation.

In this manner, the thus-configured second embodiment can also acquire agenerally similar effect to the above-described first embodiment. Inother words, the present embodiment can also generate a desired forceaccording to a condition at that time regardless of an operationcondition and whether the electric damper 43 and the gear apparatus 44are normal or abnormal.

Next, FIG. 17 illustrates a third embodiment of the present invention.According to the above-described first and second embodiments, theswitching unit is realized by the gear apparatus including the racks andthe pinion. On the other hand, according to the present embodiment, theswitching unit is realized by a flow amount adjustment apparatus thatadjusts a flow amount of the hydraulic fluid, and an attenuation damperlock apparatus that prohibits (forbids) an extension/compression of theattenuation damper. In the following description of the presentembodiment, similar components to the above-described first embodimentwill be identified by the same reference numerals as the firstembodiment, and descriptions thereof will be omitted.

A damper apparatus 51 according to the present embodiment generallyincludes an attenuation damper 52 as the force generation unit, anelectric damper 65 as the force generation unit, and a flow amountadjustment apparatus 66 and an attenuation damper lock apparatus 67 asthe switching unit.

The attenuation damper 52 includes a pair of rods 59 and 60 protrudingfrom a cylinder 53, and generates a damping force by converting motionenergy of forward or backward movements of the rods 59 and 60 into heatenergy. More specifically, the attenuation damper 52 includes thecylindrical cylinder 53 sealingly containing the hydraulic fluid such asthe hydraulic oil, a first piston 57 and a second piston 58 diplaceablycontained in the cylinder 53 and defining the inside of the cylinder 53into three chambers, a first rod-side oil chamber 54, a second rod-sideoil chamber 55, and an intermediate oil chamber 56, the first rod 59having a one-end side protruding from one end of the cylinder 53 and anopposite-end side fixedly attached to the first piston 57, and thesecond rod 60 having a one-end side protruding from an opposite end ofthe cylinder 53 and an opposite-end side fixedly attached to the secondpiston 58.

The cylinder 53 includes a cylindrical cylinder main body 53A, and afirst cover member 53B and a second cover member 53C closing respectiveopenings of the cylinder main body 53A on both end sides in an axialdirection together with respective openings of a movable element 65B ofthe electric damper 65 that will be described below on both end sides inthe axial direction, respectively. A reservoir 53B1, which contains thehydraulic fluid, is provided at the first cover member 53B. Further, theattenuation damper lock apparatus 67 that will be described below isdisposed at the first cover member 53B.

Further, a first mounting eye 61 configured to be mounted on the vehiclebody side or the bogie side is provided at one end of the first rod 59,and a second mounting eye 62 configured to be mounted on the bogie sideor the vehicle body side is provided at one end of the second rod 60.The second mounting eye 62 protrudes from a bottom portion 65A1 of astator 65A of the electric damper 65 that will be described below. Inother words, the second rod 60 and the stator 65A are fixed to thesecond mounting eye 62, and these second rod 60 and stator 65A areconfigured to be integrally displaced with each other.

Further, a first oil passage 63, which connects the first rod-side oilchamber 54 and the intermediate oil chamber 56 to each other to allowthe hydraulic oil to flow between these first rod-side oil chamber 54and intermediate oil chamber 56, is formed at the first piston 57 andthe first rod 59. A second oil passage 64, which connects the secondrod-side oil chamber 55 and the intermediate oil chamber 56 to eachother to allow the hydraulic oil to flow between these second rod-sideoil chamber 55 and intermediate oil chamber 56, is formed at the secondpiston 58 and the second rod 60.

A damping force generation mechanism (not illustrated) such as anorifice serving as a resistance against a flow of the hydraulic fluid isprovided at an intermediate position of the first oil passage 63. Thisdamping force generation mechanism restrains a flow of the fluid betweenthe first rod-side oil chamber 54 and the intermediate oil chamber 56,thereby generating a damping force between the first rod 59 and thecylinder 53. On the other hand, the flow amount adjustment apparatus 66that will be described below is provided in the second oil passage 64.

The electric damper 65 includes the stator 65A, and the movable element65B linearly movable relative to the stator 65A. In other words, theelectric damper 65 is configured as a linear motor, and generallyincludes the bottomed cylindrical stator 65A including an armature 65Dwith coils 65C provided thereon, and the cylindrical movable element 65Bincluding a plurality of cylindrical permanent magnets 65E arranged sideby side in the axial direction.

An attachment hole 65A2 for attaching the second mounting eye 62provided at the second rod 60 is formed at the bottom portion 65A1 ofthe stator 65A. Due to this hole, the stator 65A and the second rod 60are mounted on the vehicle body side or the bogie side via the secondmounting eye 62, which is a common mounting eye. On the other hand, themovable element 65B is attached to the cylinder 53 on a radially outerside of the cylinder 53 of the attenuation damper 52. More specifically,the movable element 65B is attached to the cylinder 53 with the cylinder53 inserted therein and the openings of the movable element 65B on theboth sides in the axial direction closed by the cover members 53B and53C of the cylinder 53.

The flow amount adjustment apparatus 66 constitutes the switching unittogether with the attenuation damper lock apparatus 67 that will bedescribed below, and allows the attenuation damper 52 and the electricdamper 65 to be switched between the series connection and the parallelconnection. The flow amount adjustment apparatus 66 is disposed at acertain position of the oil passage 64 between the attenuation damper 52and the electric damper 65. The flow amount adjustment apparatus 66increases or reduces an opening area of the second oil passage 64through which the hydraulic fluid passes, and is switched among, forexample, a fully opened state in which the opening area is maximized, acompletely closed state in which the opening area is zero, and anopening area reduction state as an intermediate state between them (astate between the fully opened state and the completely closed state).

The attenuation damper lock apparatus 67 is located between theattenuation damper 52 and the electric damper 65 and is attached to thefirst cover member 53B. The attenuation damper lock apparatus 67prohibits (forbids) a relative movement between the cylinder 53 and thefirst rod 59 (a forward or backward movement of the first rod 59relative to the cylinder 53). The attenuation damper lock apparatus 67includes an engagement pin 67A configured to be engaged with the firstrod 59, and prohibits a relative movement between the cylinder 53 andthe first rod 59 by engaging the engagement pin 67A with the first rod59 when locking the attenuation damper 52. On the other hand, theattenuation damper lock apparatus 67 disengages the engagement pin 67Afrom the first rod 59 by retracting the engagement pin 67A from thefirst rod 59 when unlocking the attenuation damper 52. As a result, thefirst rod 59 is allowed to move relative to the cylinder 53.

Next, an operation of the damper apparatus 51 according to the presentembodiment will be described.

When the flow amount adjustment apparatus 66 is in the fully openedstate, the hydraulic fluid smoothly flows between the second rod-sideoil chamber 55 and the intermediate oil chamber 56, and the second rod60 can be freely displaced relative to the cylinder 53. In this case,the railway vehicle can be placed into the active operation using theelectric damper 65 alone, by causing the attenuation damper lockapparatus 67 to lock the attenuation damper (to prohibit the first rod59 from being displaced relative to the cylinder 53), thereby

On the other hand, when the flow amount adjustment apparatus 66 is inthe completely closed state, the hydraulic fluid is blocked (prohibited)from flowing between the second rod-side oil chamber 55 and theintermediate oil chamber 56, thereby prohibiting (forbidding) the secondrod 60 from being displaced relative to the cylinder 53. In this case, adamping force can be generated between the cylinder 53 and the first rod59 by causing the attenuation damper lock apparatus 67 to unlock theattenuation damper 52 (allow the first rod 59 to be displaced relativeto the cylinder 53). As a result, the railway vehicle can be placed intothe passive operation (the series connection) using the attenuationdamper 52 alone.

On the other hand, when the flow amount adjustment apparatus 66 is inthe opening area reduction state, the flow of the hydraulic fluid can berestrained between the second rod-side oil chamber 55 and theintermediate oil chamber 56, and a damping force can be generatedbetween the second rod 60 and the cylinder 53. In other words, the flowamount adjustment apparatus 66 functions as a damping force generationmechanism that generates a damping force between the second rod 60 andthe cylinder 53. In this case, the railway vehicle can be placed intothe parallel operation state (the parallel connection) in which theattenuation damper 52 and the electric damper 65 can operate in parallelby causing the attenuation damper lock apparatus 67 to lock theattenuation damper 52.

In this manner, the thus-configured third embodiment can also acquire asimilar effect to the above-described first and second embodiments. Inother words, the present embodiment can also generate a desired forceaccording to a condition at that time regardless of an operationcondition and whether the electric damper 65 is normal or abnormal.

The above-described first and second embodiments have been describedbased on the example in which the electric damper 14 or 43 is realizedby the direct-drive linear motor. However, the present invention is notlimited thereto. For example, an electric damper 71 may include arotational motor 71A including a stator, and a rotation-linear motionconversion mechanism 71B (a ball screw mechanism or the like) includinga movable element, like a first modification illustrated in FIG. 18 anda second modification illustrated in FIG. 19. In this case, FIG. 18corresponds to a modification of the first embodiment, and FIG. 19corresponds to a modification of the second embodiment.

The above-described first and second embodiments have been describedbased on the example in which the gear apparatus 15 or 44 is configuredin such a manner that the pair of racks 17 and 18 or the pair of racks45 and 46 are meshed with the pinion 19 or 47 including the single toothportion 19A or 47A. However, the present invention is not limitedthereto. For example, a pinion 81 may be configured to include toothportions 81A and 81B having different outer diameters from each otherand the racks 17 and 18 or 45 and 46 are configured to be meshed withthe respective tooth portions 81A and 81B, like a third modificationillustrated in FIG. 20 and a fourth modification illustrated in FIG. 21.FIG. 20 corresponds to a modification of the first embodiment, and FIG.21 corresponds to a modification of the second embodiment.

In this case, a relationship among the displacement amounts of the racks17 and 18 or 45 and 46 and the displacement amount of the pinion 81 isdetermined from a ratio of the diameters of the respective toothportions 81A and 81B of the pinion 81. Therefore, the electric damper(the electric actuator) 14 or 43 can be an electric damper of alow-speed high torque or a high-speed low torque according to a settingof the ratio between the diameters of the respective tooth portions 81Aand 81B of the pinion 81, whereby the flexibility of the design can beimproved.

The above-described first and second embodiments have been describedbased on the example in which the gear apparatus 15 or 44 includes thesingle pinion 19 or 47. However, the present invention is not limitedthereto. For example, the gear apparatus 15 or 44 may be configured toinclude a plurality of pinions 91 and 92 arranged in parallel, like afifth modification illustrated in FIG. 22 and a sixth modificationillustrated in FIG. 23. FIG. 22 corresponds to a modification of thefirst embodiment, and FIG. 23 corresponds to a modification of thesecond embodiment. In this case, the strength and the durability of theportions where the racks 17 and 18 or 45 and 46 are meshed with thepinions 91 and 92 can be enhanced.

The above-described first and second embodiments have been describedbased on the example in which the switching unit is realized by the gearapparatus 15 or 44 constituted by the racks 17 and 18 or 45 and 46, andthe pinion 19 or 47. However, the present invention is not limitedthereto. For example, the switching unit may be configured in such amanner that the rod 42B of the attenuation damper 42, the movableelement 43B of the electric damper 43, and a vehicle body couplingmember 101 disposed on the vehicle body side are coupled to one anothervia a coupling rod 102, like a seventh modification illustrated in FIG.24. In this case, the coupling rod 102 swingably couples the rod 42B,the movable element 43B, and the vehicle body coupling member 101 viarotational support members 103 such as bearings and pins. FIG. 24corresponds to a modification of the second embodiment.

The above-described first and second embodiments have been describedbased on the example in which a damper capable of exerting a constantdamping force is employed as the attenuation damper 13 or 42. However,the present invention is not limited thereto, and for example, may beconfigured in such a manner that a damper capable of exerting anadjustable damping force (a semi-active damper) is employed as anattenuation damper 111, like an eighth modification illustrated in FIG.25.

In this case, both the forces (the thrust force and the damping force)generated by the electric damper 43 and the attenuation damper 111 canbe adjusted (controlled) when the dampers are connected in parallel (theelectric damper 43 and the attenuation damper 111 can generate the forceof the damper apparatus 41 in cooperation). More specifically, theattenuation damper 111 is mainly in charge of a resistance force in theforce generated by the damper apparatus 41, and the electric damper 43is mainly in charge of an assist force in the force generated by thedamper apparatus 41. This arrangement can reduce power consumption whilereducing a vibration of the vehicle. Further, when the attenuationdamper 111 is in charge of the resistance force, power consumption canbe further reduced by causing the electric damper 43 to operate in aregeneration region.

The above-described first embodiment has been described based on theexample in which the pinion 19 of the gear apparatus 15 is configured tobe disposed so as to surround the central pin 6 of the vehicle body 2.However, the present invention is not limited thereto. For example, thepinion may be configured to be disposed at a position offset from thecentral pin (a pole of the traction apparatus). In other words, the gearapparatus (the switching unit) can be disposed at, for example, aportion between the vehicle body and the bogie that does not interferewith another member according to the configuration between the bogie andthe vehicle body, the configuration of the traction apparatus, and thelike. The same also applies to the second and third embodiments.

The above-described respective embodiments have been described based onthe example in which the damper apparatus 12, 41, or 51 as the forcegeneration mechanism is configured in such a manner that the attenuationdamper 13, 42, or 52 and the electric damper 14, 43, or 65 are mountedon the vehicle such as the railway vehicle (between the vehicle body 2and the bogie 5 thereof) while being horizontally placed. However, thepresent invention is not limited thereto. For example, the forcegeneration mechanism may be configured in such a manner that theattenuation damper and the electric damper are mounted on a vehicle suchas an automobile (between a vehicle body and an axle thereof) whilebeing vertically placed.

The above-described respective embodiments have been described based onthe example in which the damper apparatus 12, 41, or 51 as the forcegeneration mechanism is mounted on the vehicle. However, the presentinvention is not limited thereto. For example, the damper apparatus maybe applied to an electromagnetic suspension used for various kinds ofmachines, buildings, and the like that serve as vibration sources.

According to the above-described embodiments, it is possible to generatea desired force according to a condition.

More specifically, the force generation apparatus can switch the oneforce generation unit and the another force generation unit between theseries connection and the parallel connection by the switching unit.Therefore, the force generation apparatus can generate the desired forceusing one or both of the one force generation unit and the another forcegeneration unit by switching the series connection and the parallelconnection with use of the switching unit according to the condition.

According to the embodiments, the switching unit can switch theattenuation damper and the electric damper between the series connectionand the parallel connection. Therefore, the force generation apparatuscan generate the desired force using one or both of the attenuationdamper and the electric damper by switching the series connection andthe parallel connection with use of the switching unit according tocondition. In this case, for example, by setting the series connectionwith use of the switching unit and locking (fixing) one of theattenuation damper and the electric damper, the force generationapparatus can use the other damper alone. Further, for example, theforce generation apparatus can acquire forces from both the attenuationdamper and the electric damper by setting the parallel connection withuse of the switching unit.

According to the embodiments, the switching unit is constituted by theracks and the pinion, whereby the force generation apparatus can stablytransmit the force via the switching unit regardless of whether theswitched state (the operation mode) is the series connection or theparallel connection. In this case, the switching unit can be constitutedby the pinion and the pair of racks meshed with the pinion. One of therod and the cylinder of the attenuation damper, and one of the statorand the movable element of the electric damper can be mounted on the onemember. Any of the three members, the pinion and the pair of racks canbe mounted on the other of the rod and the cylinder of the attenuationdamper. Any of the remaining two members can be mounted on the other ofthe stator and the movable element of the electric damper. The remainingone member can be mounted on the other member.

According to the embodiments, the frictional force of the gear of thepinion is variable. Therefore, the switched state can be switched to,for example, the series connection by setting the frictional force tozero (allowing the pinion to freely rotate). On the other hand, theswitched state can be switched to, for example, the parallel connectionby maximizing the frictional force (prohibiting the pinion fromrotating). In this case, the passive state and the active state can beswitched by providing the lock apparatus (the brake apparatus) thatlimits (blocks or prohibits) a relative movement(extraction/compression) to at least one of the one force generationunit (for example, the electric damper) and the another force generationunit (for example, the attenuation damper).

According to some embodiments, the force generation mechanism isconfigured to be used as the left-right movement damper disposed betweenthe vehicle body and the bogie, and therefore can stably generate thedesired force between the vehicle body and the bogie according to thecondition. As a result, the performance of the railway vehicle can beimproved.

REFERENCE SIGNS LIST

-   2 vehicle body (one member or the other member)-   5 bogie (the other member or one member)-   12, 41, 51 damper apparatus (force generation mechanism, left-right    movement damper apparatus)-   13, 42, 52, 111 attenuation damper (force generation unit)-   13A, 42A, 53 cylinder-   13B, 42B rod-   14, 43, 65, 71 electric damper (force generation unit)-   14A, 43A, 65A stator-   14B, 43B, 65B movable element-   15, 44 gear apparatus (switching unit)-   17, 18, 45, 46 rack-   19, 47, 81, 91, 92 pinion-   20 pinion brake apparatus-   59 first rod-   80 second rod-   66 flow amount adjustment apparatus (switching unit)-   67 attenuation damper lock apparatus (switching unit)-   102 coupling rod (switching unit)

1. A force generation mechanism configured to be mounted between twomembers that are one member and the other member relatively movable toeach other, the force generation mechanism comprising: a plurality ofdirect-drive force generation units; and a switching unit disposedbetween one and another of the force generation units and capable ofmechanically switching the one and the another force generation unitsbetween a series connection and a parallel connection.
 2. The forcegeneration mechanism according to claim 1, wherein the switching unitswitches a ratio of forces generated by the one and the another forcegeneration units by mechanically connecting the one and the anotherforce generation units in series or in parallel.
 3. The force generationmechanism according to claim 1, wherein the one force generation unit isan attenuation damper including a rod protruding from a cylinder andconfigured to generate a damping force by converting motion energy of aforward or backward movement of the rod into heat energy, and whereinthe another force generation unit is an electric damper including astator and a movable element linearly movable relative to the stator. 4.The force generation mechanism according to claim 1, wherein theswitching unit includes a rack and a pinion.
 5. The force generationmechanism according to claim 4, wherein a frictional force of a gear ofthe pinion is variable.
 6. The force generation mechanism according toclaim 1, wherein the one member is a vehicle body, and the other memberis a bogie, and wherein the force generation mechanism is a left-rightmovement damper apparatus.
 7. The force generation mechanism accordingto claim 6, wherein a pneumatic spring configured to support the vehiclebody swingably relative to the bogie in a vertical direction and aleft-right direction is provided between the vehicle body and the bogie.8. The force generation mechanism according to claim 6, wherein the rackis mounted on each of the rod of the attenuation damper and the movableelement of the electric damper, and the pinion is mounted on the vehiclebody.
 9. The force generation mechanism according to claim 8, whereinthe pinion is disposed concentrically with a rotational center of thebogie.
 10. The force generation mechanism according to claim 2, whereinthe one force generation unit is an attenuation damper including a rodprotruding from a cylinder and configured to generate a damping force byconverting motion energy of a forward or backward movement of the rodinto heat energy, and wherein the another force generation unit is anelectric damper including a stator and a movable element linearlymovable relative to the stator.
 11. The force generation mechanismaccording to claim 2, wherein the switching unit includes a rack and apinion.
 12. The force generation mechanism according to claim 3, whereinthe switching unit includes a rack and a pinion.
 13. The forcegeneration mechanism according to claim 2, wherein the one member is avehicle body, and the other member is a bogie, and wherein the forcegeneration mechanism is a left-right movement damper apparatus.
 14. Theforce generation mechanism according to claim 3, wherein the one memberis a vehicle body, and the other member is a bogie, and wherein theforce generation mechanism is a left-right movement damper apparatus.15. The force generation mechanism according to claim 4, wherein the onemember is a vehicle body, and the other member is a bogie, and whereinthe force generation mechanism is a left-right movement damperapparatus.
 16. The force generation mechanism according to claim 5,wherein the one member is a vehicle body, and the other member is abogie, and wherein the force generation mechanism is a left-rightmovement damper apparatus.